Engineering design synthesis  understanding, approaches and tools

Understanding

Senses of synthesis

1.1.1 General meanings of synthesis and analysis

In the early 1960s, systematic design methods began to emerge across various professional fields, highlighting the importance of synthesis in design theory and methodology Synthesis is often viewed as the creative phase of problem-solving, essential for generating ideas, as "without ideas there is nothing to analyse or to choose between." While design is primarily associated with synthesis and science with analysis, both processes are interrelated and essential components of a unified method This chapter will also explore the critical role of analysis in the design process.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002

The term "synthesis" originates from the Greek words sunthesis, meaning collection, and suntithenai, meaning to put together In essence, synthesis refers to the process of combining or assembling various elements—such as ideas, substances, activities, or processes—into a cohesive whole This process transforms simple concepts into more complex ones, integrates species into genera, and merges individual propositions into comprehensive systems Additionally, it encompasses the unification of components across various fields, including electrical, mechanical, hydraulic, and pneumatic systems, as well as the aggregation of preferences into value functions.

Synthesis is usually treated as the opposite of analysis

The term "analysis," originating from the Greek word "analusis," means to unloose or resolve something into its basic elements It involves a detailed examination of the components of a subject, such as the words in a sentence, the notes in a melody, the statements in an argument, or the chemical elements in a compound More broadly, analysis refers to the careful study of something to enhance understanding and facilitate conclusions.

The term "synthesis" describes the comprehensive outcome of synthetic activity, while "analysis" refers to the detailed examination of constituent elements and their interrelationships.

In the philosophy of science, "synthesis" and "analysis" have distinct meanings; "analysis" involves breaking down knowledge into its foundational principles and is linked to inductive reasoning, while "synthesis" refers to reasoning from general principles to specific conclusions, aligning with deductive reasoning For instance, in Newton's Method, analysis entails deriving general principles from observations, whereas synthesis involves deducing consequences from those principles This terminology can be confusing, particularly in design contexts, where "synthesis" denotes the creative generation of ideas, diverging from deductive reasoning Additionally, "analysis" can pertain to problem analysis and the examination of product behavior, often relying on deductive methods.

1.1.2 Synthesis and analysis as phases of the design process

In writings on design theory and methodology the processes of "synthesis" and

Analysis can be interpreted in two distinct ways: firstly, as phases within the design process, and secondly, as essential functions that should be integrated into any effective problem-solving methodology.

Influential early works on systematic design include Archer's "Systematic Method for Designers" and Iones' "Method of Systematic Design," both of which outline a linear process comprising synthesis and analysis stages Synthesis involves generating potential solutions for subproblems and constructing comprehensive designs, while analysis focuses on identifying subproblems and developing performance specifications Iones' model further incorporates an evaluation phase following analysis and synthesis, whereas Archer emphasizes a six-stage approach that includes synthesis as a key component.

Fig.1.1 Archer's model ofthe product design process

"analysis" formed the creative he art of his model, to which he added "programming" and "data collection" at the beginning, and "development" and "communication" at the end (see Fig 1.1)

Archer and Jones emphasized the importance of thoroughly analyzing the design problem before exploring potential solutions They believed that designers should begin by meticulously identifying relevant factors and establishing performance limits on functional variables Only after this comprehensive understanding should the designer proceed to develop partial solutions, ensuring a more effective design process.

The process of synthesizing ideas into a cohesive design proposal aims to foster innovative solutions By distinctly separating synthesis from analysis, designers can liberate themselves from preconceived notions and avoid early fixation on existing solutions.

In the early 1970s, design methodologists criticized the traditional "linear" perspective of the design process, asserting that designers are required to prestructure their problems to effectively solve them.

The "analysis-synthesis" model of design is based on a flawed understanding of inductive logic in science, highlighting the necessity for designers to draw on their existing knowledge of solutions Influenced by Popper's scientific methodology, Hillier et al and Darke introduced design models that prioritize the importance of conjectures In these frameworks, designers initially formulate a solution conjecture, which is then analyzed and evaluated, reversing the traditional sequence where analysis comes before synthesis or conjecture.

Despite significant criticism of the traditional analysis-synthesis-evaluation model, the concepts of analysis and synthesis continue to be recognized as distinct phases in the design process As a result, many design projects are still organized and documented according to these phases.

1.1.3 Synthesis and analysis as functions of problem solving

Systems engineering, which emerged in the late 1950s, introduced a unique perspective on synthesis and analysis Hall's classical account of systems engineering methodology identifies synthesis and analysis as two of seven interrelated functions that form the core logic of systems methodology He emphasized that these functions are not linearly related and do not follow a necessary time sequence, distinguishing them from the phases of a generic system's life cycle Instead, they represent classes of activity applicable across various fields, with the logic of systems methodology being integral to every phase, serving as the underlying structure of the systems engineering process.

Hall defines synthesis as the process of gathering, exploring, or creating a collection of ideas, alternatives, or options The main goal of synthesis is to compile a comprehensive list of hypothetical systems, each developed in sufficient detail to assess their alignment with specific objectives For Hall, synthesis encompasses a spectrum from reconfiguring existing components to inventing entirely new concepts, utilizing techniques that vary from logical reasoning to psychological approaches.

Table 1.1 Hall's morphology of the systems engineering process

Elements 01 the 2 3 4 5 6 7 line structure logic -+ Problem Value Systems Systems Optimisation Decision Planning delinition system synthesis analysis oleach making lor action {problem design {collect {deduce altemative (application (toimple-

Phases finding {develop and conse- (iteration 01 01 value ment next olthe and objectives invent quences 01 steps 1-4 system) phase) coarse context and alternatives) alternatives) plus structure T1me~ analysis) criterion) modelling)

2 Project ~l planning (and preliminary design)

4 Produc\ion (or Aô construction)

6 Operations (or Asl As7 consumption)

7 Retirement A7l A72 A76 An and phase out)

Hall disagrees with Archer and Jones, who link analysis primarily to problem-solving Instead, Hall defines systems analysis as the process of deducing relevant consequences of various decisions and actions based on a specified value system These deductions can encompass aspects such as quality, market dynamics, reliability, cost, effectiveness, and quality of life The dual use of the term "analysis" can lead to misunderstandings and debates, particularly regarding whether synthesis should occur before or after analysis, as the meaning of "analysis" differs in Archer and Jones' frameworks.

"problem analysis", whereas for Hillier et al and Dark "analysis" is the deduction of the consequences of a conjecture

The logic of synthesis

Synthesis plays a crucial role in addressing design problems by linking intended functions to the structural description of designed objects It is a form of plausible reasoning, encompassing various types such as analogy, induction, statistical generalization, and abduction This article explores which pattern of plausible inference is most representative of the transition from function to form, questioning whether it is primarily abduction or another reasoning pattern Understanding these reasoning modes is essential for simulating the design process through computers and developing practical design machines, ultimately enhancing our comprehension of design itself.

To effectively address design problems, it is essential to analyze the structure of a product, which is defined by its physical form This form encompasses both geometrical aspects, such as shape and dimensions, and physico-chemical characteristics, including the materials used for each component Together, these elements constitute the overall design of a new product.

The form of a product determines its properties, such as weight, strength, hardness, and color While we often categorize these properties, we inherently assert that certain hypothetical statements are valid For instance, stating "the stiffness of this construction is such and such" implies that if the construction is subjected to a specific load, it will deform in a predictable manner Each property provides insight into how the product will react when placed in a particular environment and used in a specific way, ultimately describing the expected behavior under defined conditions.

Intensive properties, like specific gravity, are solely dependent on the physico-chemical form, while extensive properties, also known as "thing properties," are influenced by both intensive properties and the object's geometric form, such as weight In product design, extensive properties are particularly crucial, as they directly impact the product's functionality.

Products are designed with specific functions that enable them to effect change in their environment, including their users These functions can be articulated through various representations, such as everyday language, mathematical formulas, or as a "black box." Regardless of the format, statements regarding these functions reflect the intended behavior of the product and often take a hypothetical form For instance, when grinding coffee, we aim for a final state (S2) that produces ground coffee of a specific granule size, starting from an initial state (S1) characterized by particular coffee beans, energy availability, and stable temperatures This relationship can be expressed as a proposition: if S1 occurs, then S2 will follow.

S2)' Unlike properties, statements about functions are normative A product either has certain properties or does not have them, irrespective of the purpose of auser Functions, however, are imposed On products

1.2.2 Reasoning from funetion to form

When designing a new product, it is crucial to consider not only its intended functions but also its form, as the latter influences its extensive properties A product's effectiveness is often revealed only when it is used in specific ways and environments While some properties are immediately observable, many only manifest when the product is engaged correctly For instance, iron rusts only when exposed to water, and a ballpoint pen writes effectively only on horizontal surfaces Therefore, a product will perform as intended only if utilized in accordance with the designer's specifications This understanding of use, alongside the product's form, is essential to solving the design problem.

Figure 1.3 illustrates that a product's actual behavior is influenced by its structure and the conditions of its use, with arrows indicating causal relationships By understanding the form and usage of a product, one can predict its properties and functionality through deduction or experimentation However, designers must work in reverse, starting from a desired function to inform their design choices.

Fig 1.3 The funetioning of a produet

Fig 1.4 The funetional behaviour of a crowbar

F, designer must think up the form and its use The reasoning from form to function is usually called "analysis", whereas the reasoning from function to form is called

"synthesis" [22] Notwithstanding the importance of analysis, in design the essential mode of reasoning is synthesis, for without an idea of form and use there is nothing to analyse

To illustrate the principles outlined in Fig 1.3, consider a crowbar example (see Fig 1.4) A crowbar can be characterized by specific attributes, such as being made of steel, measuring 850 mm in length, and having a 30 mm diameter Its primary function can be defined as "amplifying force," where an initial force (FI) applied to the crowbar results in a consequential force (F2) Given the crowbar's design, including its dimensions and material, we can utilize mechanical formulas to predict F2 based on FI, assess its bending, and evaluate its ability to withstand stress This deductive reasoning allows us to determine whether the crowbar possesses the necessary properties to perform as intended, leading to a definitive conclusion: for a specific form and applied force (FI), there exists a unique corresponding force (F2).

A crowbar serves multiple functions beyond its primary use, demonstrating that different environments and applications lead to various transformations Each transformation aligns with a specific function, such as that of a hammer However, mechanical formulas cannot definitively determine a crowbar's shape based solely on its function, as the required stiffness and strength can be achieved through various materials, shapes, and dimensions By arbitrarily selecting all but one degree of freedom, one can uniquely identify the remaining form factor Furthermore, the relationship between function and form is complex, as amplifying forces can also be achieved through alternative technical principles like pulleys, gears, hydraulics, or even newly invented mechanisms.

Synthesis, the process of reasoning from function to form, is inherently creative and involves the integration of scientific and technical knowledge Causal models guide critical decisions such as selecting physical effects, technical principles, materials, geometric shapes, and key dimensions However, this process does not yield a single definitive answer, as the potential solutions are virtually limitless.

Now, which type, or pattern, of non-deductive inference is typical for the transi- tion from function to form?

1.2.3 The pattern of reasoning of synthesis

In product design, one can deduce properties and performance characteristics from the description of a product's form and intended use This inference follows a logical pattern: if a product is made of aluminum (premise p), then it does not corrode (conclusion q), based on established rules (p ~ q) Designers often begin with ideas about a product's functions rather than a detailed description, which leads them to define its geometrical and material attributes Consequently, performance requirements (q) are derived from the design statements (p), highlighting the crucial role of deduction and empirical generalizations in the design process.

P 7 q if X is of aluminium then x does not corrode q (it is required that) x is of aluminium conclusion p x is (to be made) of aluminium

Abduction, a term coined by philosopher Ch.S Peirce, is a reasoning pattern distinct from deduction Unlike deduction, where conclusions necessarily follow from premises, abduction infers the antecedent from the consequence This means that abduction cannot simply reverse a deductive system.

Many authors believe that the abductive reasoning pattern exemplified in the previous example is typical of reasoning from function to form However, I previously demonstrated that this perspective is inaccurate Peirce categorized two distinct reasoning patterns under the term "abduction."

The distinction between explanatory (non-creative) abduction and innovative (creative) abduction is crucial in understanding problem-solving in design While explanatory abduction follows a traditional reasoning pattern, innovative abduction leads to new solution principles for design challenges, highlighting the need for creative thinking in the design process.

When designing a kettle, its primary function is to boil water, which involves transforming water from a temperature of 20°C to 100°C This process highlights the kettle's purpose in changing an object within its immediate environment, emphasizing the importance of functionality in product design.

Introduction

Significant progress in practical design often arises from both small and large inventive steps, which are uniquely generated by the human mind While these inventive steps are inherently human, systematic approaches can effectively stimulate the creative process A crucial precursor to successful invention is gaining deep insight into the problem at hand.

The most effective systematic aids in engineering are specialized rather than general, exemplified by tools like the Linde-Frankl column for air liquefaction, which significantly reduce the need for human creativity While some aids can almost deliver inventions, such as the optimal gear tooth form, they primarily serve as support, leaving critical judgment and execution to the designer Valuable design principles encapsulate the insights of experienced designers, facilitating quick, minor innovations Additionally, various design platforms can enhance a designer's efficiency and output, a topic explored further in Chapter 12 of this book.

The opportunistic designer

Experienced designers often approach real design in a less systematic manner than what is typically recommended by academic institutions Their familiarity with the problem area allows them to understand the challenges effectively, leading to more intuitive and practical design solutions.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002 know where there is scope for progress and often have several ideas they are waiting for an opportunity to try out They may not formally construct a table of functions and possible means, but they have its contents in their heads and ideas where there is scope for improvement (and they are probably right most of the time)

Implementing a streamlined system can be beneficial, but it's crucial not to spend excessive time on complex procedures that don't directly relate to engineering science, where real progress occurs A systematic framework that includes problem analysis, conceptualization, embodiment, and detail stages, along with a simple table of functions and alternatives, as proposed by the writer in 1971, is sufficient for most needs This approach helps to identify next steps and minimizes the risk of overlooking potential opportunities, a common challenge even with structured aids.

A remarkable video showcases the innovative techniques of A.E Moulton, a renowned engineering designer known for his inventions of Hydrolastic and Hydro-gas suspensions, as well as a pioneering range of record-holding bicycles While the video may not fully represent the high standards and personalized approach of Moulton, it highlights key similarities between industrial designers and academic researchers.

Althollgh I advocate these props, I know full weH that the opportunistic designer, as he may be called [5], willleave them behind when the bit is between his teeth and he is away at a gallop, concatenating ideas and spotting possibilities at every step He already works through the stages and he is inwardly conscious of the functions and the options for means (but he dismisses silly ones out of hand, and just occasionally one that is not silly along with them) Usually though, he will not write all this out

He knows which choices are easily and safely made and which off er real alternatives

Understanding the significance of various elements is essential for effective design, particularly when selecting specific functions like r2 for rand and s1 for s, as these choices impact the overall embodiment While simple charts may require minimal effort, their utility should not be underestimated Ultimately, the most beneficial resources for the opportunistic designer are tailored, task-specific aids that enhance the design process.

The term "opportunistic" is often viewed negatively, but in this context, it refers to the innovative inventors behind our material civilization, who possess immense value that is frequently underappreciated These individuals exemplify a "catch-as-catch-can" design approach, characterized by their ability to seek out resources and opportunities to confidently initiate their creative processes.

As an opportunistic designer working with the esteemed engine manufacturer Napier, I have closely followed a structured design process that includes problem analysis, conceptual design, embodiment, and detailing Although I did not utilize the last stage of this sequence, I ensured that the documentation for each phase was thorough and distinctive, reflecting the best practices I observed during my time there.

Paralleis with mathematics

Mathematical and engineering inventions are closely related, with insights from mathematicians aligning with this perspective In the early 20th century, significant attention was given to the concept of invention within the field of mathematics.

The ideas stemming from Poincare's insights into mathematical invention are highly relevant to engineering design Poincare argued that the ability to identify valuable combinations among numerous possibilities is crucial for original thinkers, describing this talent as an aesthetic experience due to the joy it brings Similarly, in engineering, the thrill of discovering a harmonious interaction between elements inspires inventors to explore and develop their ideas further This phenomenon, which I refer to as the p-aesthetic, captures the excitement of recognizing a promising conjunction that fuels creativity and innovation in design.

Recently, I encountered the aesthetic appeal of a model aero-engine, specifically a small single-cylinder four-stroke internal combustion engine designed for model aircraft This engine features a conventional piston, connecting rod, and crankshaft, but with a unique vertical crankshaft and horizontal piston movement It utilizes a 2:1 reduction bevel gear to drive the horizontal propeller shaft, which is advantageous for matching most internal combustion engines with various airscrews While the design is functional, it stands out due to its low frontal area, a significant benefit for both small and large aircraft.

The innovative design of the rotating cylinder valve engine features a propeller shaft that doubles as the cylinder and incorporates the valve mechanism The cylinder's tubular extension acts as a rotary valve, aligning with inlet and outlet ports in the casing during a single engine cycle, which consists of four piston strokes At the start of the induction stroke, the rotary valve aligns with the inlet port, allowing the piston to draw in the air-fuel mixture During the exhaust stroke, it aligns with the exhaust port, facilitating the release of combustion byproducts This streamlined rotary valve system simplifies the traditional camshaft and poppet valve setup, resulting in an engine with only four moving parts.

Bevel gears the advantages of a four-stroke engine, together with low frontal area and reduction gearing

Poincaré proposed the idea of a "mechanical sieve" to filter through vast combinations of mathematical entities to identify those with potential However, he ultimately dismissed this notion, highlighting the overwhelming number of elements, interactions, and variations that make such a sieve impractical Even with the rise of computers, which excel at repetitive tasks, they still fall short of the advanced discrimination needed to tackle this complexity effectively.

The inventive process is traditionally divided into four key steps: preparation, incubation, illumination, and verification During the preparation phase, the inventor conducts thorough research in their chosen field This is followed by incubation, where the inventor engages with unrelated topics, allowing their subconscious to process the gathered information Illumination occurs when a breakthrough idea emerges, often as a unique combination of concepts Finally, in the verification stage, the new idea is rigorously tested, and its implications are explored.

Though I have doubts about incubation as a necessary step, these ideas describe weIl enough the common experience of designers

Visual thought has been a significant focus for mathematicians and scholars, highlighting the debate on the role of language in cognitive processes While some argue that language is crucial for higher-level thinking, it is evident that profound human insights often occur beyond verbal expression, suggesting that complex ideas can be challenging to articulate in words.

Combinatory play is a crucial aspect of productive thought, occurring prior to the formation of logical connections expressed through words or other communicable signs In my experience, these elements primarily manifest as visual and, to some extent, muscular sensations.

Einstein's perspective aligns with Poincaré's emphasis on the combinatory nature of thought, challenging the notion that language is crucial for advanced cognition This view resonates with the practical experiences of engineers and undermines the argument that his reasoning relied solely on the language of mathematics.

Research indicates that the brain region responsible for visual thinking is significantly larger than that dedicated to language processing This extensive area of the brain is highly specialized for visual and related information processing, functioning at an advanced level.

I The elements are those that are subject to the combinatory play I take the last sentence to mean that Einstein was an arm-waving physicist

The motion of higher animals, such as gibbons swinging through trees, closely resembles a rapid simulation of their intended trajectory, allowing them to determine the necessary route and motions for execution This process is refined through feedback from both vision and proprioception, suggesting a concept of "visual thinking." This dynamic simulation involves not only visual input but also motor and proprioceptive systems The writer proposes that the gibbon's ability to imagine its future path may have parallels in human evolution, indicating that human imagination could have originated from the visual-motor-proprioceptive system's simulative functions.

Engineering design fundamentally relies on visual thinking, a fact that is widely acknowledged While readers may not engage in expressive gestures themselves, they can certainly appreciate the significance of such visual communication in the design process.

As an example of visual thinking in science, Maxwell on Faraday is fascinating

Maxwell greatly admires Faraday's ability to achieve significant results through powerful visual concepts rather than relying heavily on mathematics He himself provides three proofs for one of his propositions, highlighting one particularly elegant proof that requires exceptional visual imagery.

Insight

Inventive steps are essential to design, driven by critical insights that enhance our understanding A prime example of such an invention is Watt's separate condenser, which significantly improved the efficiency of the steam engine by dramatically reducing coal consumption This innovation played a pivotal role in propelling the Industrial Revolution forward.

For 50 years, the Newcomen engines operated by condensing steam in the cylinder through the introduction of cold water, which kept the cylinder walls cool As a result, during the subsequent out stroke, fresh steam was required to warm these walls, leading to nearly two-thirds of the steam being wasted without contributing to piston work James Watt analyzed the Newcomen engine and recognized this inefficiency, ultimately leading to the straightforward yet revolutionary invention of the separate condenser.

By opening a valve to an adjacent vessel where cold water is sprayed, a spray condenser is created, allowing the cylinder to remain hot while the condenser stays cold This innovative approach significantly reduces coal consumption to just over one-third, greatly enhancing the economic efficiency of steam engines and creating new applications for their use However, at the time, the lack of design precedents made this inventive leap far from obvious.

In 1760, Watt's fascination with the steam engine began when he received a model for repair while working as an instrument maker at the College of Glasgow After several years of intense contemplation, he successfully invented his groundbreaking steam engine in 1765, inspired by his reflections during walks on Glasgow's Green.

It is certainly a case that fits Poincanfs stages

Watt's dismissal of the steam turbine, although not historically significant, showcased his remarkable insight into engineering Concerned about competition, his partner Boulton worried that the steam turbine could rival their engine In response, Watt asserted that the turbine would only be practical if the blades operated at 1,000 ft/s, acknowledging the potential for future advancements His foresight proved accurate, as it took over a century for the technology to develop, with a threshold of 500 ft/s being sufficient This perspective was rooted in the pioneering engineering principles he had applied to steam at a time when the field was still in its infancy.

In 1935, Robert Watson-Watt presented a brief yet impactful paper to the UK Committee for the Scientific Survey of Air Defence, demonstrating the potential of land-based radar to detect incoming bombers His concise argument, composed of fewer than 200 words, utilized straightforward arithmetic that required minimal calculation tools, highlighting the innovative approach to air defense technology.

The renowned Spanish civil engineer, Torroja, emphasized that a structural designer must deeply understand the mechanics of the structure, akin to knowing how a stone falls or an arrow flies However, achieving such profound insight is uncommon, and we often begin with limited understanding, gradually enhancing our knowledge throughout the design process.

In mechanieal and dvil engineering at least, visual thought is essential in arriv- ing at the level of insight of which Torroja wrote

Designers entering a new field should quickly cultivate their insights by examining all aspects numerically, performing rough calculations, and cross-checking results Insight-Developing Studies (IDSs) serve as a valuable tool in this process, enhancing the designer's understanding and perspective.

IDSs should prioritize simplicity In exploring the practicality of using a mass moving relative to a wave energy collector (WEC) as a reaction source, we find that with an alternating force amplitude of 2 MN, a net force of 1 MN is achievable after accounting for radiation A 1,000-tonne mass would require an acceleration of 1 m/s² to react this force, necessitating a movement amplitude of approximately 2 meters, which is manageable While smaller masses with larger amplitudes could be considered, a more detailed analysis may soon be necessary, though the concepts remain clear and understandable.

An abstract perspective can significantly enhance insights, particularly in engineering design For instance, a bolt can be conceptualized as a stiff, short piece of string, ideally utilized solely for pure tension rather than shear or bending This understanding is crucial in the design of components like cylinder heads and big ends Moreover, it's beneficial to acknowledge that the optimal connection between structural elements is often the absence of a joint, allowing for uninterrupted material flow, as exemplified in big ends.

The absorption refrigerator serves as a fascinating example, illustrating three levels of abstraction that aid in understanding its functionality By conceptualizing the refrigerator as a reversed distillation column, one can glean valuable insights for enhancing its performance, drawing directly from principles of distillation engineering.

Developing insight

The terms should be articulated as verbs and nouns, such as "store liquid" or "guide striker," rather than using phrases like "liquid tank" or "striker slide," which imply preconceived notions about the nature of the objects involved.

To make meaningful progress, it is essential to transform abstract ideas into tangible forms, ensuring that these concepts are effectively embodied and presented in a convincing manner.

To assess your understanding of a problem, consider whether you can confidently answer any related questions and estimate relevant quantities This reflective approach helps gauge the depth of your insight Ideally, a designer should maintain a comprehensive view of the entire system, allowing for immediate recognition of the relationships between different components As Torroja suggested, a designer should be able to mentally encompass the whole structure simultaneously, a task that is straightforward for simple phenomena like a falling stone or an arrow in flight However, achieving this level of comprehension can be challenging in more complex scenarios, such as with a wave-energy converter.

Insights help clarify problem areas, allowing for a more manageable understanding of complex issues This approach is particularly effective in redesign scenarios, where selective quoting can enhance clarity and focus.

To grasp the scheme of things entire and then

Re-mould it nearer to the Heart's Desire!

(with apologies to Fitzgerald and Omar Khayyam).

Design principles

Design principles serve as essential yet often overlooked tools for designers, with many being unaware of their significance While some designers may know a few principles and apply others unconsciously, the full potential of these guidelines remains underexplored Initially, I overlooked one crucial principle in my list, despite frequently utilizing it In this article, I will present five illustrative examples.

The principle of using minimal constraints for locating or guiding bodies has been recognized since the mid-19th century, significantly influencing instrument design and gas turbines This concept can be summarized as "use the minimum constraints necessary" or more informally, "let it all float about, and sort itself out." It is widely applied in metrology and instrument design, exemplified by the mounting of theodolites, which utilize three feet with various types of supports to remove specific degrees of freedom This method ensures that the theodolite is fully constrained without being over-constrained, thus preventing issues like "stiction" and irregular movement that can arise from over-constraining Modern coordinate measuring machines (CMMs) serve as prime examples of this principle in action.

Kinematic design encompasses the addition of extra degrees of freedom to effectively balance forces Helicopter rotor blades are equipped with two hinges at their roots: a drag hinge that rotates around a vertical axis to manage horizontal forces, and a flap hinge that operates around a horizontal axis to address vertical forces.

In epicyclic gears, allowing the sun pinion, annulus, or planet carrier to float helps balance the loads on the planet gears A stiff planet carrier is necessary to prevent torque-induced load concentration on gear teeth, but rotational freedom for the planets around a radial axis can promote self-alignment This approach led to significant weight savings in the Napier Gazelle helicopter gas turbine, where planet gears were mounted on diaphragms for flexibility, complemented by a lightweight planet carrier Similar results were achieved by Hicks in his Compact Orbital gearing through the use of flexible pins.

The author has recently identified a principle that highlights the efficiency of electric motors compared to solenoids This is illustrated by the fact that solenoids are significantly larger than electric motors when performing the same task The key difference lies in the motor's ability to utilize its working space, specifically the air gap, multiple times during operation, unlike the solenoid, which only uses it once.

Operating a cylinder and piston at higher revolutions per minute can enhance power output, though limitations exist due to factors like piston speed in engines and rotor surface speed in electrical machines, which can impose constraints on compactness In hydraulic machinery, performance diminishes due to the inertia of the working fluid, impacting economical compactness This principle also favors higher frequencies; for example, in wind turbines, the aim to eliminate step-up gearing between the turbine shaft and generator has led to the use of numerous poles to increase the frequency of the air gap Although the generator must remain large in diameter, the high frequency of use allows for a reduction in the material quantity within the magnetic and electrical circuits.

The wind turbine embodies the small, fast principle with its narrow blades that rotate at speeds approximately ten times greater than the wind speed at their tips, efficiently harnessing energy from a large volume of air while using minimal materials This high rotational speed not only optimizes energy capture but also lowers the costs associated with step-up gears or generators, as the expenses for these components correlate closely with their torque capacity.

The small, fast principle is very obvious, but in some cases it may be overlooked

Fig 2.2 WASA diesel big end

The importance of matching is well recognized in key areas, especially in the relationship between driver and driven components, yet it is frequently overlooked in less obvious aspects, such as aligning the stiffness pattern of a big end with the oil film demands in its bearing An unconventional big end design, as illustrated in Figure 2.2, features a split shank that adapts to the bearing ring's deflection, significantly enhancing load capacity by approximately 40% In contrast, the conventional single shank design creates a rigid point in the big end, akin to a brick under a mattress, whereas the innovative design resembles a yielding hammock, effectively distributing stress Interestingly, despite its seemingly rigid appearance, a simple dimensionless parameter reveals that the massive big end's deformation is indeed significant.

2.6.4 "Prefer pivots to slides and flexures to either"

The preference for pivots over slides is well established in various fields due to their numerous advantages Pivots, as noted by Watt, are cheaper and easier to manufacture, have no exposed working surfaces that require protection, typically involve less friction, and are simpler to seal When flexible elements can replace pivots or slides, they eliminate the need for lubrication, reduce stiction—which is particularly beneficial in instruments like CMMs—and prevent wear A striking example is modern helicopter rotor heads, which have substituted traditional drag and flap hinges with a flexible link that bends and twists to control pitch, significantly simplifying a previously complex system Similarly, both designs of epicyclic gears with self-aligning planets utilize flexures, as ensuring pivots operate without excessive residual friction can be challenging.

2.6.5 "Where possible, transfer complexity to the software"

In mechatronics, effective design often features simple yet sophisticated mechanical components, with complexity managed through advanced software For instance, in Coordinate Measuring Machines (CMMs), rather than achieving precise orthogonality in the axes—which can be costly—it is more economical to accept slight inaccuracies and rely on software to rectify these errors This approach contrasts with Suh's principle, which suggests that the optimal solution requires minimal information; however, the CMM method, despite needing more data, ultimately proves to be a superior solution.

Systematic synthesis

Engineering science often focuses heavily on analytical methods while giving less attention to systematic synthesis While synthesis can be achieved for certain design components, there are instances where engineering science handles most of the work, particularly in structural designs like discs and frames, as well as in thermodynamic applications such as steam power cycles and gas separation However, starting points for some projects can be elusive, as seen in the design of extensible sheets for liquid natural gas tank walls Conversely, some concepts, like the integration of wind turbines with heat pumps, become clear and manageable once the appropriate starting point is identified.

In the design of simple products like clothes pegs, balancing functionality and ease of use is crucial A study highlighted the challenge of ensuring a secure grip while allowing for a convenient "half-a-hand" operation, especially when supporting heavy items Traditional wooden pegs effectively address this issue by securely holding the line and item in place, but they lack the ability to store strain energy efficiently A proposed alternative, made from a single piece of plastic, offers improved energy storage and lower production costs, yet it presents usability challenges due to the complex movements required for operation.

Systematic synthesis involves developing insights and describing key properties such as "half-hand operation" and "shear strength," which are essential for preventing pegs from pulling together under heavy loads Additionally, it emphasizes the importance of design principles, including the concept of matching, to enhance functionality and efficiency in design.

By addressing the components of a problem in a systematic order, it is possible to achieve genuine systematic synthesis, particularly in specific cases, as illustrated in Section 2.8 Although many engineers may not be well-versed in the mechanics of sea waves, the core concepts of the argument remain understandable.

Insight and systematic invention in power from sea waves

Harnessing energy from sea waves presents a significant challenge in renewable energy design due to the vast array of potential solutions available.

In the late 1970s, significant advancements in wave energy technology began in the UK, driven by the Central Electricity Generating Board's preference for large devices like the Salter duck However, Norwegian innovators Budal and Falnes recognized the advantages of smaller units, which utilize resonance to generate larger movements and increase power output per unit area These small units can effectively capture energy from wave fronts more than twice their width, unlike larger devices that are limited to their own width This concept is akin to a radio antenna, where a narrow design can harness energy from its surroundings Small wave-energy collectors, typically under 30 meters in size, are referred to as "point absorbers" because they are perceived as a single point by the waves.

In an abstract view of wave power, a body floating in the sea experiences wave forces that cause it to move To harness energy from this body, a reaction force opposing the wave force must be applied, with a recommended magnitude of around 1 MN for the small units suggested by Budal and Falnes This reaction force is a critical element in wave power systems, playing a vital role in their functionality.

The Wave Energy Converter (WEC) operates as a floating body with a working surface that interacts with ocean waves, generating a net wave force countered by a reaction The instantaneous power output is determined by the product of this net wave force and the velocity of the working surface The WEC is designed as a resonant mass-spring system to enhance the amplitude and velocity of the working surface, typically achieving speeds up to 2.5 times the particle velocity of the waves.

The resonance insight is crucial as it reveals the importance of the spring function for achieving resonance, which may have otherwise been excluded Additionally, this insight highlights the need for a reaction function that could easily have been overlooked.

The primary movement of the working surface in marine environments can be categorized as "heave," which refers to vertical up and down motion, or "surge," which describes horizontal movement in the direction of the waves In smaller bodies of water, these two types of motion are the most significant and are not strongly influenced by other factors.

Imagine a vertical square working surface oscillating around a horizontal axis at its center When the surface rotates clockwise, the top half pushes water to the right while the bottom half pulls an equal amount from the right, resulting in a minimal net effect at a distance Consequently, this alternating rotation, or pitching, generates only small waves This illustrates the action of a well-functioning system.

The WEC operates by creating wave patterns that interfere destructively with incoming waves, reducing their amplitude and energy This process allows for the capture of energy, despite some losses Simple experiments, such as using a square of plywood in water, demonstrate the ineffective coupling in pitch, while similar analyses eliminate other motion types, ultimately highlighting heave, surge, and their combination as the primary effective motions.

After determining that a resonant point absorber is the most cost-effective choice, we can create a straightforward table, Table 2.1, outlining the key remaining options.

To achieve resonance in a mass-spring system, a spring is essential Similar to a pendulum, gravity acting on a weight exhibits comparable characteristics This method is often more appealing than using a gas spring, which can suffer from leaky seals and requires costly, high-quality manufacturing.

A small device anchored to the seabed could provide a reaction, but the high wave forces during storms would require a robust and costly structure In contrast, a longer device experiences varying wave forces along its length, which largely balance each other due to phase diversity, eliminating the need for an additional reaction source Therefore, this option has been excluded as it is not applicable for point devices.

Table 2.1 Simple table of options for point absorber

Line Funenon spring provide reaction motion

1 gravity spring sea bed heave

Means or Means or contiguration configuration

Gas spring systems can utilize amplitude diversity in their design, specifically by leveraging the difference in wave amplitude that decreases with depth However, this approach presents challenges similar to those found in thermodynamics, where a low work ratio results in diminished net power output due to negative work counteracting positive work.

The concept of "reacting against a mass" may initially seem unpromising, but a straightforward IDS, as previously outlined, effectively assesses the practicality of this idea, revealing it to be surprisingly feasible.

Function 3 involves motion, where surge can harness the energy of a wave front with a wavelength divided by n, while heave can only capture half of that energy However, heave is effective with waves from any direction A key distinction is that surge requires horizontal movement of the reaction mass, whereas heave necessitates vertical movement, leading to significant energy cycling and losses.

The concrete design, illustrated in Fig 2.4, features a paddle oriented towards the waves, equipped with a weighted handle for stability This paddle serves as the working surface and the ballast, creating a unified resonant system that efficiently combines functionality During operation, the paddle pitches vigorously as indicated by the arrow, requiring an alternating moment of appropriate size and phase for effective movement Our preferred method involves a sliding mass (shown in Fig 2.4), which faces resistance from hydraulic rams that primarily function as pumps These rams power a hydraulic motor connected to a generator, allowing for optimal motion and power capture, even in challenging sea conditions Further mechanics are detailed in Ref [18].

Summary

Design evolves through both incremental and significant innovative steps, often stemming from deep insights rooted in engineering science Effective design necessitates a thorough exploration of engineering principles and the cultivation of these insights, with various methods proposed to enhance this process.

• Insights can often be linked together in "logical" chains, providing systematic design These chains are special to the design in question and constitute ad hoc inventing engines

• Some links in these chains may be breakable, often by an inventive step, and may become branch points leading to novel designs

• Design principles, such as have been described, are a great help to the designer

We express our sincere gratitude to Keith Lawes, the designer of the rotating cylinder valve engine (Fig 2.1), and to RCV engines for their contributions Additionally, we acknowledge Wartsila Diesel for their work on the WASA diesel engine big end (Fig 2.2).

The author explores the limitations of traditional gear-tooth forms, questioning whether improvements can be made beyond the involute design To address this, an equation is derived for the local relative radius of curvature (R) at the contact point between two gears of general form, expressed in relation to the distance (x) from the pitch point and the sine of the pressure angle (y).

The formula for the local load capacity of the teeth in a gear system is represented as R = {y + x(2p + 1 - k) + X²[p² + (1 - k)p - k]}/(1 - k), where k denotes the gear ratio and p signifies dy/dx This indicates that the overall capacity of the gearing is directly proportional to C.

The value of C is proportional to (1 + k) times the integral of C with respect to x along the path of contact Among the terms in R, only the term in p² presents significant potential for increasing C indefinitely As p rises, the radius of curvature grows with the square of p, while the length of the path of contact decreases inversely with p Consequently, the overall effect results in an increase in the term in R that is directly proportional to p.

The practical increase in load capacity is constrained, as the banana-shaped contact area eventually extends beyond the tooth's top and bottom However, by implementing a rapid change in the pressure angle, it is possible to design gears that can support approximately twice the load capacity of well-engineered involute gears.

Wildhaber invented a new type of gearing in 1923, which offers approximately twice the load capacity of traditional spur gearing This innovation was later reinvented by Novikov around 1955, leading to its common designation as "Wildhaber-Novikov" gearing Despite its superior strength compared to well-designed involute gearing and relatively straightforward manufacturing process, it has not gained significant market traction This lack of adoption can be attributed to the fact that a twofold improvement may not be compelling enough to warrant a shift from established solutions However, in applications like helicopter reduction gears, where minimizing weight is crucial, this gearing could prove to be highly advantageous.

One reason it failed to do so may have been the failure to apply the design prin- ciple of least constraint

All gearing, except for involute types, is sensitive to center distance, but can operate effectively if allowed to float perpendicularly to the mean pressure line This principle was demonstrated by D.C Johnson in 1959 with Wildhaber-Novikov gearing If excessive constraints are applied, any weight advantages may be negated by increased structural stiffness A similar scenario is seen in the Gazelle engine gearbox, where involute gearing benefits from rotational freedom, enabling self-alignment and reducing the need for a heavy, rigid spider.

[1] Ruhemann M The separation of gases Oxford University Press, 1949

[2] French MJ An annotated list of design principles Proc lust Mech Eng 1994;208:229-34

[3] French MJ Conceptual design for engineers 3rd ed Springer, 1998

[4] The innovative engineer Smallpeice Trust, 74 Upper Holly Walk, Leamington Spa, CV32 4JL [in VHS only, with script]

[5] French MJ The opportunistic route and the role of design principles Res Eng Des 1992;4:185-90

[6] Hadamard J The psychology of invention in the mathematical field Dover, 1944

[7] Poincare H Seience and method London: Nelson, 1924

[8] RCV engines, on http://www.rcvengines.com

[9] Motluk A Read my mind New Sei 2001;169(2275):22

[10] Maxwell Jc In: Niven WD, editor Scientific papers, vol 2 Dover, 1965; 17l-8

[11] Dickinson HW, Jenkins R James Watt and the steam engine London: Camelot, 1989

[12] Rosgren C-E Diesel engine design aspects for heavy fuel operation Proc Inst Mech Eng 1985; 199:251-3

[13] Suh NP The principles of design Oxford University Press, 1990

[14] Hemp WS Optimum structures Clarendon, 1973

[15] French MJ A measure of utility of parts of plane frames Proc Inst Mech Eng C; 1999;21:623-8

[16] French MJ Systematic design of an extensible sheet for LNG carrier tanks In: Proceedings 6th International Offshore and Polar Engineering Conference, vol 4, 1996; 529-32

[17] Salter SH Power conversion systems for ducks IEE Conference on Future Energy Systems, Institution of Electrical Engineers, London, 1979

[18] French MJ Tadpole: a design problem in the mechanics ofthe use of sea wave energy Proc Inst Mech Eng 1996;210:273-7

[19] Thorpe T Wave energy review ETSU Report R26, Dec 1992

[20] French MJ Gear conformity and load capaeity Proc Inst Mech Eng 1966;180:1-4

[21] French, MJ Invention and Evolution 2nd ed Cambridge University Press, 1994

Synthesis and theory of knowledge: general design theory as a theory of knowledge, and its implication to design

Abstract design knowledge is essential for effective product synthesis, with General Design Theory (GOT) modeling this knowledge as a topology and offering theorems related to design This article reviews GOT, highlighting its limitations while demonstrating how, despite its unrealistic assumptions, it can still offer valuable insights for the development of computer-aided design systems.

Introduction

Knowledge is a complex and subjective concept, often viewed through two main lenses: the structural view, which defines knowledge as the content of a representation, and the functional view, which sees knowledge as the ability to solve problems.

A comprehensive understanding of design requires integrating both structural and functional perspectives, as neither can independently produce effective designs Knowledge exists in the balance between these two extremes, highlighting the importance of their interplay in creating meaningful representations.

Synthesis involves creating artifacts that meet specific requirements, representing an activity that ranges from understanding synthesis to the ability to execute it effectively Among various mathematically based design theories, General Design Theory (GDT) stands out for its aim to explain human design processes and inform the development of computer-aided design (CAD) tools GDT emphasizes the structure of design knowledge, asserting that its mathematical foundations enable strong conclusions about design processes Specifically, if design knowledge is viewed as a topology encompassing all possible artifacts, successful design occurs when specifications, represented within this topology, are met Additionally, GDT links design directly to synthesis, ensuring that the completion of synthesis results in a valid design rather than one that merely requires validation.

Perfect topological structures of knowledge are often unrealistic, as design results do not align well with these topological assumptions; any imperfection in the knowledge structure undermines its potential Although the extended version of General Design Theory (GDT) aims to address this issue by altering the assumptions, it continues to face comparable limitations Consequently, it is reasonable to scrutinize the effectiveness of these approaches.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002 contribution of GDT to real design beyond its "historical" landmark contribution to design theory

This chapter provides an informal overview of Geometric Dimensioning and Tolerancing (GDT) and its significance in design, referencing a more comprehensive formal review elsewhere It begins by illustrating the application of GDT models in design through a straightforward example Next, it outlines essential guidelines for developing CAD systems influenced by GDT Finally, it touches on recent advancements in mathematically based design theories that extend beyond GDT, situating it within a broader context.

The domain of chairs

Figure 3.1 illustrates eight chairs, collectively known as the chairs domain, which are utilized to clarify the concepts explored in this chapter Each chair is labeled with a letter, and their functionalities are summarized in Table 3.1 In this table, a "+" indicates that a chair offers a specific function, while a "-" signifies its absence.

Scandinavian office wheel "bean-bag" chair chair chair chair

Table 3.1 Functional properties of chairs

1 seats - prevents a downward movement of the body

2 supports bock - supports an upright posture revolves - revolves around a vertical axis

4 movable - can be easily moved

5 constrains bock - constrains backward movement of back

6 easy to monu(o((ure - has a simple design with standard components + - + - +

Table3.2 Observable properties of chairs

Each chair not only serves a functional purpose but also possesses observable properties that define its attributes and structure, as summarized in Table 3.2.

The relationship between a chair's structure and its functions can be complex and context-dependent For instance, a chair with wheels is movable, and one with a vertical rotational degree of freedom can revolve, although not all chairs with such features allow for complete rotation Additionally, some chairs can provide back support without a physical backrest; for example, chair A offers support due to its proximity to a wall, while chair E's structure inherently allows for back support Furthermore, certain functions can qualify others, such as how the function of constraining back movement qualifies the ability to support the back This assessment can be intricate, as chairs F and G limit back movement due to their design, whereas chairs B and C do so based on static factors In contrast, chairs D and H do not restrict back movement, and chairs A and E lack physical back support altogether.

The previous examples focused on inferring potential functionality from the structure of artefacts, which aids in analysis In contrast, design emphasizes synthesis, generating artefact structures that fulfill specific functions For instance, specifying a chair that is both movable and has a constrained back leads to two potential designs, F and G These designs can be derived in two ways: one begins with movable designs {A, E, F, G, H} and refines them with the constrained back property, while the other starts with constrained back designs {B, C, F, G} and refines them with the movable property The most succinct description of the solution is chairs featuring physical back support and wheels, although an alternative, seemingly irrelevant yet accurate description is lightweight chairs with legs.

Note that the refinement process was made easier by the use of the eight repre- sentative chairs as mediators between the specification and the design description

In the absence of these chairs, the process might have been more difficult.

GDT

A topological structure of objects offers a unique perspective on design, as topology serves as a generalization of continuity Key properties of continuity, such as continuity itself and convergence, play significant roles in various design tasks including synthesis, analysis, and redesign Continuity ensures that minor adjustments in design descriptions lead to minor changes in the functionality of artifacts, indicating that slight modifications may rectify discrepancies between a candidate's functionality and the desired function Similarly, convergence, another process-oriented concept, ensures that incremental refinements result in only small changes to functionality, emphasizing the importance of gradual improvements in the design process.

Definition 3.1 An entity is areal object that existed, exists presently, or that will exist in the future The set of all objects is called the entity set

Every chair, whether it has existed since the invention of the chair or will exist in the future, is considered an entity To simplify this concept, let's assume that Figure 3.1 represents the complete set of these entities, referred to as the entity set.

Definition 3.2 When an entity is subjected to a situation, it displays a behaviour that is called a functional property The collection of functions observed in dif- ferent situations is the functional description of the entity

The properties listed in Table 3.1 are all functional properties of chairs Table 3.1 specifies the functional behaviour manifested by each chair

Definition 3.3 The representation of an object is called concept of entity or entity

The representation of achair using the function and structure properties from Tables 3.1 and 3.2 is an entity

Definition 3.4 A dassification over the entity set is a division of the entities into several dasses Each dass is called an abstract concept The set of all abstract con- cepts is denoted by T

Chairs A and B can form one class, while the remaining chairs create another A more insightful classification emerges when considering the chairs' properties For instance, classifying based on the presence of legs divides the chairs into two categories: those with legs, including chairs C, F, and G, and those without legs, comprising chairs A, B, D, E, and H.

Definition 3.5 The set of all functions, called the function space, is the set of all the classes from all the classifications of the functions It is denoted by T; The set of all artefact descriptions, called the attribute space, is the set of all classes of all the classifications of attributes It is denoted by '10

In principle, a topology over a set with n entities can contain 2" classifications There- fore, in principle, the function (or attribute) space for the chairs domain can contain

This article discusses eight distinct functions that classify a set of chairs, focusing on specific attributes such as support back, movable, and aesthetic, which uniquely identify chair E However, not all potential classifications are applicable; for instance, combinations like easy to manufacture and aesthetic, or movable, aesthetic, and constrain back do not correspond to any chairs Additionally, the attributes has legs and is lightweight are relevant to the artefact descriptions of chairs F and G.

GDT's axioms convey the assumptions of the theory about the nature of design knowledge

Axiom 3.1 (Recognition) Any entity can be recognised or described by its attrib- utes and/or other abstract concepts

Each chair in Fig 3.1 can be distinctly identified by its unique artefact description attributes For instance, chair A stands out as the only model without vertical rotational degrees of freedom and wheels.

Axiom 3.2 (Correspondence) The entity set and its representation have one-to- one correspondence

In the context of Axioms 3.1 and 3.2, each chair depicted in Fig 3.1 is viewed as an individual entity, with its characteristics outlined in Tables 3.1 and 3.2 These axioms establish a one-to-one correspondence between the perceived objects and their conceptual descriptions While representing entities may necessitate an infinitely long list of property-values, which is impractical, the theory posits that sufficient resources exist to address this challenge.

Axiom 3.3 (Operation) The set of all abstract concepts is a topology of the entity set

A topology (5, T), sometimes denoted only as T, is a mathematical entity consist- ing of a set 5 and the set T of sub sets of 5 that satisfies the following properties:

3 for Sj E T, i E A, A a countable set, UjSj E T

The set of all abstract concepts forms a topology, which influences its structure and the operations applicable to it Axioms 3.1 and 3.3 require equal treatment of all entities within this topology The simplest topology for a set of chairs, denoted as T, consists of the empty set and the set itself Another topology, known as the discrete topology, is represented by the power set of the chair set, containing 256 elements However, these topologies lack complexity A more interesting topology can be constructed with subsets that differentiate between various classes of entities, ensuring it adheres to the three essential properties of topology.

Definition 3.6 Ideal knowledge is the one that knows all the entities and can describe each of them by abstract concepts without ambiguity

In the chairs domain, this assumes that one can recognise that two chairs are differ- ent through observing their attributes, which is clearly correct for the chair domain

To ensure clear identification of each chair, it is essential to include all ten chairs in the analysis The second and third properties of topology lead to the conclusion that '10 equals 25 To streamline this process, we developed abstract concepts based on the properties outlined in Table 3.2, as illustrated in Fig 3.2 These concepts will serve as the "topologies" for the set of chairs, despite not fully adhering to traditional topological properties Each line in the figure highlights the chairs that meet the specific property indicated along the line.

In the analysis of chair functionality, certain chairs are identified with a value of "-" as indicated by the numbers in parentheses Each chair's attributes are clearly defined, as shown in Figure 3.2b, where they are enclosed by lines Figure 3.2a illustrates two pairs of indistinguishable chairs, {B, C} and {A, H}, which lack functional differentiation due to the absence of separation lines This issue can be resolved by incorporating additional functions, such as "easy floor cleaning," assigning a value of "+" to all movable chairs and "-" to chair C, and "shapeless," where chair H receives a "+" while the others get a "-" The challenge of distinguishing between entities based on functionality suggests that multiple design candidates may fulfill a given specification.

Definition 3.7 The design specification, T, E T, designates the function of the required entity by using abstract concepts

It is natural to describe the specification of an object by the intersection of abstract concepts, since the specification describes functions that the desired chair must fulfil

The specification for a chair requires it to be both movable and capable of revolving, which can be succinctly represented by the set {A, B, C, D, E, F, G, H} A viable solution to this design challenge can be found within the subset {A, E, F, G, H} However, if the design must also prioritize ease of manufacturing, the relevant subset would be {A, F, H}, leading to an intersection that results in {A, E, F, G, H} n {A, F, H}.

{A, F, H} We see how the second property of topology is used to identify the set of candidate designs for each specification

Definition 3.8 A design solution is an entity 5 that is included in its specification and contains its necessary manufacturing information

Theorem 3.1 The entity concept in the attribute space '10 is a design solution that is represented by the intersection of classes that belong to '10 Each of the attrib- utes can be perceived as manufacturing information a

Fig 3.2 a Funetion and b attribute "topologies':

The attribute space comprises observable properties essential for manufacturing an entity, defining a design solution This concept is formalized in Definition 3.9, which builds upon the intuitive understanding of design outlined in Section 3.1 Additionally, Theorem 3.2 clarifies the nature of design within the context of ideal knowledge.

Definition 3.9 Design process is the designation of a domain in the attribute space 'To that corresponds to a domain specifying the specification in T

Summary

This section comprises four chapters that outline a prescriptive approach to design synthesis, primarily grounded in theories of artifacts The approaches vary in nature and detail, with the first three chapters focusing on outcome-based methods In contrast, the fourth chapter offers guidelines for identifying areas of improvement in products and implementing those enhancements Collectively, these chapters present a framework for developing both function and form in design.

Chapter 6 is by Claus Thorp Hansen and Mogens Myrup Andreasen and describes the domain theory of artefacts, which has been influenced by the theory of technical systems but which has evolved into one in which an artefact is described at three levels (called domains here): transformation, organ and part Transformation between these is prescribed to take place using relationships that link functions to means, where each choice of a means leads to uncovering further functions and then to further means and so on, developing into a function-means tree In this sense, synthesis of form for a given function could be seen, in a normative sense, as one of a bootstrapping process of developing means to fulfil a function and identifying functions required as a result

In Chapter 7, Gerhard Pahl and Ken Wallace present the function structures approach, which emphasizes starting with the overall function of a product and breaking it down into simpler subfunctions This method involves identifying principles that can achieve each subfunction and integrating them into various concept variants By utilizing Krumhauer's universally applicable functions as foundational elements, they advocate for employing a morphological matrix to systematically develop alternative concept variants, ultimately fostering innovative design solutions.

In Chapter 8, Karlheinz Roth advocates for the use of design catalogues that detail various levels of artefact descriptions, enabling designers to leverage existing designs effectively He argues that these catalogues, which categorize products and their components from function to form, facilitate the reuse of knowledge in design processes Roth illustrates the diversity and practicality of design catalogues through several examples, highlighting their significance in enhancing design efficiency and creativity.

In Chapter 9, Denis Cavallucci explores the TRIZ methodology created by Genrich Altshuller, who analyzed numerous Russian patents to uncover fundamental "laws" governing innovation These laws are categorized into static, cinematic, and dynamic types, which collectively assist in pinpointing areas for design enhancement and offer strategies for improvement Additionally, Cavallucci includes an extensive reference list on TRIZ, catering specifically to English-speaking audiences.

This article explores ten chapters that highlight key research directions in computational synthesis of designs The research primarily focuses on two approaches: compositional synthesis, which involves creating solutions by combining various building blocks, and the retrieval of existing designs for modification These modifications can either adapt the original design for specific needs or transform it into new, innovative designs.

The first two chapters are on automated compositional synthesis of concepts for fulfilment of a given function

Chapter 10 is by Karl Ulrich and Warren Seering, and is one of earliest attempts at automated compositional synthesis of concepts The area of application is sensors The representationallanguage is bond graphs, the algorithm is search, and the system developed is limited to synthesis of single-input single-output systems Synthesis is performed at the topologicallevel, and the resulting concepts are intended to be eval- uated by the designer

Chapter 11 is by Amaresh Chakrabarti, Patrick Langdon, Ying-Chieh Liu and Thomas Bligh, and is on the development of FuncSION - a multiple IIO concept syn- thesis software for mechanical transmissions and devices The representation is based on systems theory and symbolic geometry, and the algorithm is search Syn- thesis is performed at three levels: topology, spatial and generic physical FuncSION has been tested using case studies, product compendia and patent catalogues The designs synthesised are intended to be evaluated, modified and explored by the designer

The next two chapters are examples of development of function into a function structure and support of compositional synthesis

Chapter 12 by Rob Bracewell explores the foundational concepts of Schemebuilder software, designed to aid in the creation of mechatronic systems that integrate mechanical, electrical, and software components The software utilizes function-means trees and bond graphs for representation, enabling designers to interactively evolve their functions and concepts through a systematic expansion of the function-means tree Additionally, the effectiveness of this software has been validated through various case study examples.

Chapter 13 is by Ralf Lossack, and is for supporting the design of physical systems The approach - DnCAD Entwurf - is a synthesis of systematic methodologies, and is based on the concept of a "working space" within which the design interacts with its inputs and outputs Synthesis is done by designers selecting and concatenating me ans from a database The software has been tested using several case studies and its use in student projects

The next two chapters are examples of retrieval of existing designs

Chapter 14 is by Tamotsu Murakami, and is on retrieval of existing mechanisms to fulfil a given, specified mechanical function The representation used is based on qualitative configuration space, and the number of designs retrieved is one in each case This has been tested using several cases, some of which are used as examples in the chapter Retrieval is based on matching of the characteristics of intended func- tion with that of the stored designs The resulting designs are intended to be explored by the designer, but that is not currently supported within the framework

Chapter 15 is by Lena Qian, and is on retrieval of mechanical, structural, hydraulic and software systems The retrieval is done using analogy at three levels: function, behaviour and structure The degree of similarity between the target and retrieved domains determines the choice of level used Retrieved designs may be from a dif- ferent discipline, and it is the task of the designer to transform the insight gained into an artefact appropriate for the domain in these cases

The next two chapters are examples of changing retrieved designs for adapting to the current purpose

Chapter 16 is by Sambasiva Bhatta and Ashok Goel, and is for adaptation using analogy The current areas of application are electronic and mechanical controllers The representation is based on logic and systems theory, and the adaptation mecha- nism is based on the use of design patterns with associated knowledge of what they can change into and how The approach has been tested using several example cases Chapter 17 is by Boi Faltings on the FAMING system for adaptation of mecha- nisms The software requires input from the designer for deciding the direction of modification and adapts the initial design using simple rules of replacement and envisionment The representation is based on qualitative configuration space This has been tested using several example cases, including those from architecture The final two chapters are on change from existing designs for gene rating inno- vative designs

Chapter 18 is by Susan Finger and James Rinderle, and is on software that uses transformational gramm ar for changing a given intended behaviour or an existing design into new, behaviour-preserving designs The current application is gear trans- missions, and the representation used is bond graphs This is one of the earliest papers that use grammars for generating designs, and is aprecursor to much work on various generative grammars, not covered in this book

Chapter 19 is by John Koza and is on software that uses genetic programming, which is based on the concept of genetic algorithms but uses programs that evolve in order to transform given designs to generate innovative designs with better per- formance in terms of the given criteria The applications are electrical and electronic circuits and chemical reactions The software has been tested using several case studies and patent catalogues

Introduction

Engineering a system, whether a product or process, requires foresight into its potential use and construction before any materials are utilized This process begins during product planning, where various markets and product options are evaluated, leading to crucial decisions about the product range an enterprise will offer This initial phase is essential for the overall health of the business Ideas generated for a product must then be converted into actionable instructions for implementation, covering aspects such as manufacturing, assembly, and packaging This translation of ideas into practical applications falls under the realm of design, which encompasses both synthesis and, at times, creativity.

To ensure effective product design, it is crucial to establish clear requirements from the outset, allowing for a focused and goal-oriented progression While intuitive and spontaneous approaches are inherent to human behavior, a structured and systematic design process—though iterative and recursive—is essential for achieving optimal solutions to the identified problems.

Systematic procedures can enhance the exploration of potential solutions, facilitating opportunistic activities It is essential to integrate and verify results from intuitive actions within these systematic frameworks The dynamic interaction between systematic and unsystematic approaches can improve the search for solutions and lead to more effective design outcomes Initial requirements, as outlined in the design specifications, play a crucial role in this process.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002 tion) should also be continually revised and updated as designing progresses, of course in consultation with the customers and their representatives

Technical systems (TSs) must not only function effectively and perform their designated duties but also possess a well-configured internal structure Engineering design, a crucial aspect of product development alongside industrial design, faces a challenging set of tasks aimed at creating viable products that meet performance standards, technical capabilities, and economic potential while appealing to customers This process emphasizes the importance of "quality" and incorporates considerations of lifecycle engineering, including energy usage, by-products, toxicity, costs, hazard analysis, and various specialized disciplines.

Engineering design is defined as the process of creating a technical system (TS) by transforming expressed needs and preliminary ideas into a comprehensive description of a manufacturable product or implementable process This transformation involves predicting and synthesizing the system's structures and behaviors before its actual existence, making it a crucial early stage in product realization The primary goal of engineering design is to produce a complete description of an optimal TS, providing manufacturing instructions, such as drawings, while considering anticipated time and cost for both design and implementation.

Design science and the theory of TSs

Science, derived from the Latin term "scientia," meaning knowledge, is defined as a field of study focused on the observation and classification of facts, particularly aimed at establishing verifiable general laws It encompasses a body of accumulated and systematized knowledge, especially in relation to the physical world.

It should, therefore, be possible to formulate a science about engineering design

Klaus emphasizes in cybernetics that relationships are integral between the subject being analyzed—whether as a product or process—and the corresponding theory and method The theory should effectively articulate the behavior of the subject through various forms such as mental, graphical, and physical models, as well as verbal explanations and symbolic or mathematical expressions, ensuring adequate precision Additionally, it should outline the methods used for operating, utilizing, and designing the subject.

The knowledge for engineering design, the "subject" under consideration, is selected, collected, cross-referenced, ordered and categorised within design science

[4] (supported by Refs [5-14]) This knowledge is divided into twO basic dasses:

1 knowledge about TS (products and their usage processes), as the operands of design processes (DesPs), and their development during the DesP;

2 knowledge about DesPs, as elements of the transformation of information from needs to full descriptions of proposed TSs

Knowledge about each of these two subjects can be classified into:

3 theoretical/descriptive knowledge (theory), and

4 knowledge and advice derived from and/or prepared for practical activities

Note that we make a distinction between theoretical/descriptive knowledge and descriptive/narrative/observational/protocol studies - the latter aims to elucidate a theory

The four-quadrant model of knowledge for engineering design, illustrated in Fig 4.1, features a horizontal axis representing items 1 and 2, while the vertical axis displays items 3 and 4 This model highlights the necessity of relationships to other forms and contents of knowledge, as depicted in the figure Notably, subdivisions of generalized knowledge can be similar in both the theory and practice quadrants for both Technical Skills (TSs) and Design Principles (DesPs).

A fundamental model for design science, influenced by systems engineering principles, is the transformation system In this model, processes are represented as rectangular symbols, while real systems are depicted with rounded corners This framework allows for the analysis and abstraction of artificial processes, identifying their elements and properties Additionally, these processes can be decomposed into their constituent operations, particularly highlighting those where a transformation system is significantly involved.

Knowledge of objects and physical phenomena

Needs requ{remenfs, constroints, demands, wishes, desires

Systems conceptualizations, configurotions, parametnzotions, etc

Know!edge (inc!uding Methodologies, Methods)

Methods for problem- solving, designing,

Knowledge of human octivity (physico/, mentoi)

informal cd hoc, intuitive, expficit instructions, implicit (e.g leomed)

- - con:;;cious personal inter-personal

Statements -+ -1 Statements about Design Processes

General theory Special theon'es:

General theory Special theon'es:

Fig.4.1 Model (map) of design science - survey

Theon'es of human behavior

psychologic.af cognitive routine creative attective psycho-motor personal inter-personal etc

Boundary of Transformation System, TrS r OPERATORS:

OPERANDS: r Od 1 Operand in State 1

Transformation process, TrP r Od2 Operand in State 2 r Secondary l: Secondary r Technology, Tg outputs inputs Secln -\:-'~ _ -=-"""""'''''''::''''''':' _ j Jt SecOut

Transformation (Tr) ehanges eertain properties of the operand (os passive member of the proeess), by mutual interaction between object and means,

Operand (Od) - WHAT is being transformed? object that is being changed in the transformation from an input state to an output state which should preferobly be more desirable

Stote aggregate (vector) of va lues of properties (Pr) of 0 system at 0 certain time

Technology (Tg) - HOW is it being tnansformed? knowledge about the translonmation, formulates what elfeets are needed

Elfects (EI) - WITH WHAT is it being transformed? means of tnansformation, actions exerted onto the operand, including the neeessary energy, auxiliary materials, regulation and contro!

Seeondary inputs (Seeln) (1) all necessary (desirable) further inputs to the pnaeess, and (2) all undesired inputs (disturbanees, contaminants, produets of the environment that enter os operands)

Seeondary outputs (SeeOut) mostly undesirable opeand outputs of the proeess \0 the enviroment, their nature end composition depend on the chosen technology

Operators (Op) the Op Hu) o~erand:

The World Health Organization (WHO) and various entities provide essential effects to living beings, especially humans, as well as animals and bacteria These effects are delivered through technical means, including artificial systems and information systems, which facilitate effective management and goal-setting By directing efforts and achieving objectives, these systems contribute to an active and supportive environment for all forms of life.

Active environment (AEnv) - WHERE is it being transformed? The part 01 the general environment that os operator influenees the transfonmation (desired and undesirable elfeets)

Space the ma in property 01 the environment (surroundings) 01 the transformation

Time - WHEN is it being transformed? time period du ring which the transfonmation occurs

Types 01 eflects aeting on the operand, secondary inputs, seeondary outputs, etc.:

materials; energy; information (including signals)

Types of operand, object being transfonmed:

biologieal objects (humans, plants, animals, ete.);

Strueture of the transformation )lroeess:

elements = operations (0), or groups of operations;

relationships :::; connections between the outputs of one operation (er group of operations) with the inputs of the immediately following operation (ar group 01 operations);

Operations can take plaee sequentially (in series) or simultaneously (in parallel)

The general model of the transformation process, as illustrated in Fig 4.2, outlines the complete transformation system and its key elements This model highlights technical processes (TPs) as a specific type of transformation, noting that in many instances, there is no direct involvement of humans, information, management, or the environment.

1 the operand (the object undergoing transformation within the TP) - the hori- zontal fiow through the rectangle depicting the process in Fig 4.2;

2 the technology and the structure of the process, those operations that are realised in the transformation process, and their connections;

3 the execution system, the operators "human" and "TSs (means)" that deliver the required physical effects (actions) to the TP - oval symbols in Fig 4.2;

4 the other operators of the process, information, management and environment systems, often only acting indirectly;

5 the secondary inputs and outputs

Transforming operands within a technical process (TP) requires the output effects generated by technical systems (TSs), which facilitate necessary actions Machine systems, as specific instances of TSs, primarily utilize mechanical modes to achieve these work effects Moreover, there is a growing trend towards hybrid systems, such as electro-hydraulic and computer-mechanical systems, particularly in their propulsion and control mechanisms.

Every technical system (TS) displays a variety of structures, as illustrated in Fig 4.3, which are inherent to the TS regardless of intentional design These structures encompass elements such as functions, organs, or constructional parts, depicted in Fig 4.4, highlighting the significance of domain theory The interactions among these elements, both within the TS and at its boundaries, play a crucial role in generating diverse effects that enable the TS to transform the operand in the transformation process (TP).

Functions describe the actions that a Technical System (TS) is capable of performing, similar to how a human hand grips a handle The main function of a TS involves internal transformation effects and is supported by auxiliary functions, which include propelling, regulating, controlling, connecting, and supporting functions These aspects are essential for classifying the functional structure of TSs.

The organs of the TS, also known as function carriers, play a crucial role in executing various functions They are composed of working and auxiliary organs, including propelling, regulating, controlling, and connecting organs, which collectively create the complete structure of the TS Receptors and effectors serve as the links between the TS and its environment, marking the beginning and end of the action chains formed by the organs It is important to note that there is seldom a direct 1:1 correlation between functions and organs.

Every function and organ, regardless of complexity, can be represented by various constructional structures The potential for creating variations is influenced by design characteristics such as input, mode of action, and the properties of the technical system (TS) It is uncommon to find a direct 1:1 relationship between organs and their constructional components These structures exist in different levels of completeness and detail, ranging from sketch layouts to detailed parts drawings.

Technical systems can be categorized into four classes based on their complexity: plants or equipment, machines, assemblies, and parts Each higher-level system is made up of lower-order systems, highlighting the hierarchical nature of these elements.

Receptors i Secondary inputs, disturbances r Secondary outputs

Function Structure (see figure 4, level 111) describes those capabilities of the

TS organs and constructional parts that are needed to deliver the effects

Every technical system comprises various structures made up of diverse elements, such as functions, organs, and constructional components The interactions between these elements across different structures are typically complex and not strictly one-to-one.

The constructional structure and hierarchy of technical systems (TSs) are defined through various examples, including a car-manufacturing facility as an industrial plant, a car as a machine, and its components such as the engine, which serves as an assembly group or module Further breakdown reveals the motor's connecting-rod assembly as another module, and the threaded stud within this assembly is identified as a constructional part.

Machine elements (MEs) are essential components of mechanical systems, ranging from simple parts like screws and pins to complex assemblies such as bearings and gearboxes While MEs generally encompass a wide variety of constructional elements, certain types are specialized for specific engineering fields, including pistons, valves, and electrical components like resistors and transducers Understanding the different degrees of complexity in MEs is crucial for effective machine design and functionality.

I Realizing the interaction between operand < -> operator, in order to oehieve the desired transformation of the operand

Delivered effeets (EI) eonform to the teehnology used for the transformation

Od 1, Od 2 ~tates of the operand

TS Process Model Process Structure / /' TS in working stote operating

Designing - general

Designing is a transformative process that generates future technical systems (TS), as illustrated in the model The design process (DesP) begins with initial information, such as requirements or problem descriptions, and aims to produce detailed descriptions of the desired TS This transformation is achieved through elementary design properties, making the identification of suitable design properties the central focus of design work.

The Design Process (DesP) can be segmented into a finite number of operations, primarily categorized into a few recurring classes, applicable across various types of DesP All operational phases of the DesP are rational, although many are executed subconsciously The DesP maintains a neutral stance towards the objects being designed, encompassing a generalized model that can be utilized for designing all types of technical systems (TS) and management systems (MS) At Level 3, the process highlights recurring basic operations, with evaluation being a key component of problem-solving.

The optimal quality of a future product in engineering design is influenced by various factors across its phases, stages, and steps, as illustrated in the DesP model (Fig 4.7) This model highlights the essential components that contribute to effective design outcomes.

All properties of teehnieol systems can be categorized into a comprehensive set of classes, with each property influencing one or more classes in various ways The distinctions between these classes are often unclear However, this classification is useful for specific applications, particularly in design work, where 12 classes of properties are deemed most suitable.

Classes 1 and 2 refer 10 Ihe Purpose of the T5 Classes J, 4, 5, 6 ond 7 refer 10 Ihe Life phoses of the T5 Closses 8, 9, 10 ond 7 1 rafer 10 Humans ond sociely Closs 72 refers 10 designing Ihe TS 10 ochieve THE ENVIRONMENT MAKES DEMANDS ON THE TECHNICAL SYSTEM which are refleeted in the EXTERNAL PROPERTIES - of the TS, i.e properties: - - that the teehnieal system carries - - that the customer eon see and judge - - that the design engineering must generate by designing (i.e by establishing the properties in class 12)

Quality encompasses the suitability and appropriateness of perceived and measured values of properties, which includes an appropriate selection of design, manufacturing, assembly, service, and usage Key sources of quality are derived from the quality of design, the quality of manufacturing and assembly processes, and the quality of service provided.

The appearance of an object, including its form, color, and surface, plays a crucial role in its coordination with the environment Essential external properties, such as functionality, can be categorized into various types: working functions that perform primary tasks, auxiliary functions that support these tasks, propelling functions that aid in movement, and regulating functions that control and connect different elements Understanding these properties is vital for effective design and interaction within various contexts.

Functionally determined properties encompass performance ratings such as speed, power, load capacity, and functional dimensions, ensuring suitability for specific duties and environments Design characteristics are defined by technological principles, action sites, and transformation operations under varying conditions Additionally, the mode of internal action plays a crucial role in determining the effects supplied to operands, highlighting the significance of these properties in practical applications.

(12) OesPr DESIGN.f>RaPERTIES ELEMENTARY DESIGN PROPERTIES

Properties under direct \ control of \ \

Arrangement abstraction in modeling encompasses various elements such as form, dimensions, materials, and manufacturing processes, while also considering surface finishes and tolerances General design properties are crucial, including strength, hardness, stiffness, and noise emission levels Additionally, it is important to address environmental factors such as pollution, decommissioning, disassembly, sorting, recycling, and waste disposal, as well as the elimination of contaminants.

Effective planning of properties involves assessing delivery capabilities, quality assurance, customer service, and market research Key operational properties include reliability, safety, lifespan, maintenance suitability, and space and energy requirements Additionally, understanding servicing requirements is crucial for optimizing manufacturing processes.

MANUFACTVRING PROPERTIES - buying in quotity Qssuronce - manufacturing - inspecting quality contral testing - etc

Mo fo fa th cturing e TS(p) erand the using e TS(p),

Desicning the TS(p) see figure DP 1)

~ Technological and organizational preparation for manufacture (production planning)

M Od;'" Manufacture and assembly of TS(p)

M Od2 Distribution (sale and delivery) of TS(p)

operation of TS(p) Transfarmation af the operand

4 Liquidation, elimination of the TS(p), reengineering, reuse, recycling, etc

TS os Operator of (partial) process

TS os Product of enterprise

M Od2 formation Od2 Requirements specificotian Contract dacuments Research reports Market reports

Description of the technieal system TS(p): drawings parts lists ca leu lotions reports

Daekets Woge slips Plans Jigs tools, fixtures i: " E c- 'ii o ,

TS(p) realized in possessfon 5 of manufacturer:g at loeation of ~ manufacture ~

TS(p) in possession of the eonsumer at the laeatian af operation Operand

V1 I- of the TP ~ using the TS(p), g in State 2 :J

Fig 4.6 General model of the life cycle of TSs

The design process involves several critical stages, including planning and layout, to ensure effective design operations It is essential to identify design technology needs and methodologies, which guide the working principles and description of requirements A well-structured system must be established, incorporating clear instructions and organized design elements to facilitate the overall design workflow.

I Detailing Operations ~ / c c ~ c'~ c: c E iò c '0 c: CIJ c: c E >",= c !!:! '-(1) (h d UlVl (1)0 (1)- UI (1) (l)Q.lC/J (/) V1C trlC/n fIllV V eno v."O' p ases an :.:;:(/') !.:::;'iJ :.=0 =(/)C = 00 ) :=.9 :':::.9.L: :':::01 [I) I!.:::;';:: -0-0

~ L _ -' ~ W ) 0 V CI 0 0 c: a 0 0 ,e Q) -0 ~ § 0 a ~ CI c: ::J E c v "iij::J c steps 00 o~ o c: 0:6:;::: 01° 0-0._ DU OU't 00 , '- 0 cC:t) llJ / 0 ~ ~u a;_u t)(fd~ (heU' 1;;1::: &;1:: 0 Uic IV 0 (;;0 00 ~a ~g w2 w't~ WI Q wEo w2 w2u wo a::: La wE uEE tl Basic / ~fions~ (Problem solving Elementary Activities

~k' , , ' 3.1 pr~~~!':n the I v.L sol~;;~~'~ 'VI I I I View I 3.5 Prepare information I ~ I

3.6 Verity, check Experiment v.v Evuluate, decide 3.4 communiculel solution I I Lead discusSlon I I Optimize ete 5

11 Speck, explain 12 Write, report 13 Sketch

The design process involves a structured hierarchy of activities, where each level encompasses specific tasks that build upon one another For instance, activities such as 'Verify' and 'Learn' are foundational to higher-level processes like 'Form-giving.' Additionally, there exists a block dependency where certain tasks are repeatedly executed in a flexible sequence, particularly within the problem-solving operations at the basic level It's important to note that 'thinking' is an internal process that cannot be directly observed or documented, although it may be considered part of the elementary activities at a higher level Understanding this structure enhances our ability to analyze and synthesize design methodologies effectively.

(a) State 2 of the processed information: a full description of a TS that completely fulfils the given requirements, as the goal (output) of the DesP;

(b) State 1 of the information to be processed: the given requirements (customers' design specification) as the input to the DesP;

(c) a DesP, a transformation of information from State 1 (a) to State 2 (b)

This transformation is realised or influenced by six operators of the process:

(d) the engineering designers (usually as member of a design team), their profes- sional profiles and personal characteristics, internalised knowledge, abilities, skills, attitudes, values, motivation, open-mindedness, adaptability, etc.;

(e) the working me ans available to the designer (tools, equipment, etc., including computers and computer-aided design programs) and their usage;

The current technical knowledge, including available information, working methods, and representation techniques, should be externalized, collected, and organized into a specialized information system Additionally, effective management is essential for providing guidance, leadership, and control over the DesP.

(h) the active environment (including time and space) in which the process takes place; and

(i) the DesP itself, the methods (procedures and techniques) employed by the designer, the technology of the process

Operators play a crucial role in determining the success of the design process (DesP), influencing the quality of the output, which includes the description of the designed technical system (TS) They also establish key parameters such as the costs and duration of the design, as well as the committed costs associated with the proposed TS.

The key elements in the design process are the designers, the available knowledge, and the design procedure While tools such as computers assist designers, they cannot independently create designs This highlights the ongoing necessity for various studies—descriptive, narrative, observational, and protocol—to explore the human, psychological, and sociological dimensions of design These studies should focus on teamwork, the contrast between routine and creative tasks, critical situations, and management dynamics.

Introduction

Engineering design encompasses diverse thought processes that can primarily be categorized into analysis and synthesis Current research modeling design processes often operates under assumptions such as "design as problem solving," "design as decision making," and "design by analysis," yet lacks a clear focus on these foundational aspects.

"design as synthesis" Compared with analysis, synthesis is less understood and codified as a model

This chapter describes an attempt to formalise and model synthesis theoretically

Theoretical approaches aim to scientifically understand synthesis and develop a model that elucidates the design mechanism and predicts design processes in various situations With a robust scientific model of synthesis, designers could receive valuable guidance, even for complex design challenges, potentially leading to the creation of an advanced intelligent design support system.

Motivated by their research interests, the authors' group has explored various aspects of design, beginning with Yoshikawa's proposal of General Design Theory (GDT) in the 1970s, which is grounded in axiomatic set theory They also investigated experimental methods, leading to the establishment of a cognitive design process model through the analysis of design protocols By formally structuring this cognitive model, they developed a computable design process model, which ultimately resulted in the implementation of a design simulator.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002

This chapter combines findings from earlier studies with the recent project "The Modeling of Synthesis," which emphasizes theoretical aspects to create a cohesive understanding of synthesis It begins by presenting our foundational perspective on synthesis In Section 5.2, we provide a concise overview of existing research on design process modeling within the engineering design community, while Section 5.3 encapsulates our prior research focused on synthesis-oriented thought processes.

In Section 5.4, we differentiate between synthesis and analysis, leading to the development of two thought-process models: one focused on analysis and the other on synthesis We emphasize the importance of logical reasoning within these models and propose a multiple model-based reasoning framework designed to support advanced design systems for verifying synthesis models This framework posits that synthesis is fundamentally a knowledge-based activity, prompting us to analyze design processes as knowledge operations Consequently, we introduce a knowledge operation model that breaks down operations into logical and modeling components Logical operations facilitate reasoning, while modeling operations pertain to design object models within the multiple model-based reasoning framework.

Logical operations inherently include abduction, which occurs within a model-based reasoning framework designed for object modeling This type of abduction is specifically model-based In Section 5.5, we present an algorithm for model-based abduction It is essential to test the knowledge operation model against real design processes and validate it through computer implementation of the multiple model-based reasoning framework Section 5.6 focuses on evaluating the knowledge operation model against a reference model from a real design case, along with its verification through computer implementation Finally, Section 5.7 provides a summary of the discussions.

Related work

The design process is primarily examined through three lenses: theoretical, methodological, and empirical The methodological approach, often referred to as "prescriptive," is prevalent among researchers in German-speaking regions and emphasizes the ideal practices of design This approach defines design as a systematic procedure that starts with analyzing the required function, followed by breaking it down into subfunctions These subfunctions are then realized through mechanisms that demonstrate physical phenomena essential for achieving the desired outcome.

The empirical approach to design analysis is rooted in experimental results, exemplified by protocol analysis Various methods exist for analyzing design protocols, as demonstrated by Cross et al in the Delft protocol workshop, where participants utilized uniform protocol data to facilitate comparisons among different design process models While these models effectively described the phenomenological aspects of the design process, they did not uncover the underlying principles or driving forces behind design.

The theoretical approach to design focuses on establishing a top-down model for the design process, aiming to create "descriptive" design models A notable example of this approach is the GDT framework developed by Yoshikawa's team at the University of Tokyo.

[1] For modelling the design process as logical reasoning, many researchers (e.g., see

Researchers have suggested formalizing design processes through abduction, a logical reasoning method introduced by C.S Peirce Abduction involves generating hypothetical explanations, such as deriving fact p from the rule p ~ q and the premise q.

In design, the abductive process involves deriving a "design solution" from existing "design knowledge" and the characteristics of the solution itself However, due to the less formalized nature of abduction compared to deduction, initial studies focused on formalizing abduction, which hindered a clear understanding of the synthesis process.

The engineering design research community has not yet developed a unified scientific model of design processes due to the independent nature of various studies This paper aims to establish a coherent theory of design processes, particularly emphasizing synthesis To address this challenge, Blessing proposed a framework for comparing design process models, while Grabowski et al organized a workshop to explore the potential for a universal design theory by examining and relating different design theories.

Design process modelling

Several research groups have sought to scientifically analyze and model design processes Our team, starting with Yoshikawa's GDT, concentrated on both theoretical and empirical methods outlined in Section 5.2 This section provides a brief overview of our group's key accomplishment [14], which serves as the basis for the discussions in Section 5.4.

Takeda et al conducted a study on the modeling of design processes, beginning with experimental design sessions and protocol analysis They introduced a cognitive design process model that conceptualizes design as a repetition of unit design cycles, which include five key steps: problem awareness, suggestion, development, evaluation, and decision-making This model was further formalized into a computable design process model, where the suggestion phase utilizes abductive reasoning, while development and evaluation rely on deduction Additionally, circumscriptions are applied to revise knowledge in the event of contradictions The model features two levels of reasoning: object-level and action-level (meta-level), facilitating control over the object-level reasoning.

A design simulator was developed based on a computable model, successfully playing back design protocols from experiments While it utilized various reasoning methods, including deductive, abductive, and meta-level reasoning, the simulator could only mimic design processes rather than autonomously create designs, falling short of achieving a synthesis model.

A formal model of synthesis

In this section, we present our formal model of synthesis, which encompasses not only synthesis but also the broader spectrum of design activities, including analysis Prior to delving into the specifics of synthesis and analysis, we will introduce key fundamental concepts.

Decision on a Problem to be Solved

Conel Decision on a Solution to be Decision on an Action to be

Fig.5.1 Cognitive design-process model

0: Operations Ko: Knowledge on objects

Fig 5.2 Computable design-process model

(CAN_JUHP JJU HANYl (IOOLTIHE J.JIl 60S) (VOLTAGE 1.5V) (POWER_UNn J.JIl 1.5V) (ENERGYE1>

(RELEASE J 1 (U (STORE J.JIl Ei) ã'Add neu knowledSiI! lD the 1 Material flow 0 Main function System boundary

Fig 7.2 Function structure for the packing of carpet tiles

== Material flow c::J Main function - Signal flow [:::: Auxiliary function - System boundary

The function structure for packing carpet tiles incorporates auxiliary functions to enhance the design process By identifying all necessary subfunctions, designers can break down the task into manageable subtasks and subproblems This analysis streamlines the design task, allowing for a focused approach to developing solutions for each individual subfunction Adopting a flexible methodology is essential for effectively organizing the designer's work and structuring the overall solution.

Task-specific functions are derived directly from the design task at hand and are articulated using precise terminology related to the task For instance, in the case of carpet tiles, all identified functions are task-specific, fostering a strong connection to the problem being addressed This direct expression of functions not only stimulates but also guides the creative process in a problem-oriented manner Therefore, it is advisable to consistently employ task-specific functions during the initial phases of solution exploration.

Several authors have proposed the idea of generally valid functions within design methods In theory, these functions can be structured so that the lowest level consists solely of generally valid functions that are indivisible This represents the highest level of abstraction in function definition.

Characteristic input (ll/output (0) Generally valid functions Symbols Explanations

Type Change Type and outward form of 1 and 0 differ 1 1

Pressure A, '~A' CI: extension atwilt 5 F1 F 1 : KUSUlI '" 2 10 A2 > A 1 (f) ~

Pulse _ _ F, ,: n ' ~ in line m VI 1:=lI m, ::1 \~, K ,,10 100 612 < 61 1 trans- 8 -i- F,

Energy mission ' l " 6/,-lf-Af, storing 9.2 9.3 9.4

Recoit atwi lt 9 -.,:-:" ? F! : : ' ,,:::: Aô PD

The solution catalogue for the function of "replicating mechanical force" operates without the need for supplementary energy It includes a block diagram representation and a detailed form, featuring classification criteria, a primary section, selection characteristics, and an appendix for additional information.

In system theory, energy can be stored, transferred, and combined, as classified in previous studies These energy states play a crucial role in design theory by facilitating general functions Power changes are viewed solely as outcomes of these processes, leading to a classification based on a standard scale Importantly, each action—whether transferring, saving, or combining—excludes the possibility of the others occurring simultaneously.

The "Effect" column in the second section follows a similar structure, focusing solely on a single effect that influences power multiplication With all effects clearly identified, it's easy to ascertain if any are absent and to identify which ones are missing Additionally, rows 7-9 highlight the effects of "volumetric spring stiffness," "pulse transmission," and "recoil action."

In contrast, the design catalogue does not contain possible magnetic and elec- trieal power multiplications They are excluded, because only "mechanical power multiplications" are considered here

The "Force Direction" column facilitates easy handling and testing of geometrical and qualitative considerations It allows for immediate determination and testing of whether forces intersect, run parallel, are perpendicular, or align in various directions.

The structuring considerations discussed in the example are based not only on the

When making decisions, it's essential to move beyond simple "yes" or "no" answers and consider a broader range of options However, the fundamental solutions necessitate that selecting one attribute excludes the possibility of choosing another Consequently, non-unique comparisons, such as "large versus small," "hot versus cold," or "expensive versus cheap," do not serve as effective criteria for classification.

The structured system ensures comprehensive and systematic content generation, covering mechanical force multiplications through various tools such as wedges, levers, ropes, pulleys, and more Each tool is represented in the main section, while the selection characteristics in the solution catalogue facilitate choosing a suitable force multiplier based on specific properties An optional appendix provides detailed documentation of the content Although the selection characteristics and appendix can be modified or expanded, the classification criteria remain fixed, allowing only examples, formulas, and sketches to be updated in the main section.

The example in Fig 8.4 shows the use of a commonly used jointed connection

[11] in which a small force must produce a large force in order to remove the cork from a wine bottle This represents a corkscrew [1]

Row 1 of Fig 8.4 lists again the capabilities for principles of the force multipliea- tion from Fig 8.3; row 2 shows their use to produce corkscrews

Various corkscrew designs can achieve the effects illustrated in Fig 8.3, with the exceptions found in boxes 2.1 and 2.8, which introduce new mechanisms Box 2.1 features a corkscrew that utilizes a knee lever, while box 2.8 employs an innovative approach where the bottle is secured with an applied spiral, and the weight is forcefully struck against the upper shoulder, effectively using the impulse principle to "hammer out" the cork.

Requirements placed on design catalogues

To create an effective design catalogue, it is essential to achieve near-complete coverage of the processed subarea while ensuring that there are no redundancies among individual forms The content must be free from duplication, easily expandable, and accessible Expansion is possible for selection characteristics and appendices, but for content, it relies on the ability to fill in "white boxes"—areas left blank for future information This concept mirrors the periodic table of elements in chemistry, where unfilled spaces prompted the discovery of new elements Similarly, design catalogues may contain unknown solutions represented by these "white boxes."

Desirable forms of design catalogue

Design catalogues provided in table form on paper have two major forms: one- dimensional catalogues, Fig 8.6 (and also Figs 8.1 and 8.3), and two-dimensional catalogues, Figs 8.5 and 8.7

In one-dimensional design catalogues, each new category is organized into its own row, as illustrated in Fig 8.6 For example, Fig 8.1 demonstrates how every involute gearwheel, differentiated by the number of teeth, is displayed in a separate row.

Classifying Main part Selection Appendix criteria characteristics

I 1I 1lI Equ Sk Ex F V Pr Doc

C a - 8 b - 9 Fig 8.6 Strueture of a one-dimensional design eatalogue with dassifying criteria, main part, selection characteristics, and appendix

Classifying criteria and selection a b c d e characteristics

Fig 8.7 Strueture of a two-dimensional design eatalogue with classifying criteria and selection characteristics

Two-dimensional design catalogues feature a structured layout with headings in both the column and row, allowing contents to be organized at their intersections It is essential to apply the classifying criteria as selection characteristics simultaneously.

It is also possible to have three-dimensional catalogues when the contents are con- tained in two-dimensional catalogues and a third structure is present that spreads over several pages

A systematic representation is optimal for storing design catalogue contents on a computer, allowing for easy retrieval at any time Additionally, there have been efforts to create comprehensive catalogue hierarchies, enabling an overview catalogue row to be expanded into a detailed catalogue.

Use of design catalogues

It is favourable to use existing design catalogues [1]

1 Object catalogues: consists of systematically structured variants of objects

2 Solution catalogues: selection of a functional solution Fitting this solution with the demands of the special case afterwards

3 Operation catalogues: these describe the different methods to vary the objects

[1] Roth K Konstruieren mit Konstruktionskatalogen, vol II, Konstruktionskataloge 3rd ed Berlin Heidelberg: Springer, 200 l

[2] Roth K Franke H-J, Simonek R Aufbau und Verwendung von Katalogen für das methodische Konstruieren Konstruktion 1972;74(11):449-58

[3] Roth K Aufbau und Handhabung von Konstruktionskatalogen VDI-Berichte Nr 2l9, 1974; 89-99

[4] Roth K Design models and design catalogues In: ICED-Conference, Boston, 17-20 August, publica- tion series WDK 13 Zürich: Heurista, 1987; 60-7

[5] VDI 2222-2 Konstruktionsmethodik, Erstellung und Anwendung von Konstruktionskatalogen [Design engineering methodics Setting up and use of design catalogues] Berlin: Beuth Verlag, 1982

[6] Roth K Zahnradtechnik: Evolventen-Sonderverzahnungen Berlin Heidelberg: Springer, 1998

[7] Roth K Konstruieren mit Konstruktionskatalogen, vol I, Konstruktionslehre 3rd ed Berlin Heidelberg: Springer, 2000

[8] Orth B Einführung in die Theorie des Messens Stuttgart Berlin Cologne Mainz: Verlag W Kohlmann,

[9] Roth K Zahnradtechnik: Stirnrad-Evolventenverzahnungen Berlin Heidelberg: Springer, 2001

[10] MacFariane AG] Engineering systems analysis London: George G Harrap, 1964

[11] Roth K Konstruieren mit Konstruktionskatalogen, vol III, Verbindungen und Verschlüsse 2nd ed Berlin Heidelberg: Springer, 1996

[12] Diekhửner G Erstellen und Anwenden von Konstruktionskatalogen im Rahmen des methodischen Konstruierens Dissertation, TU Braunschweig, 1981 Fortschrittberichte der VDI-Zeitschriften, Reihe 1 No 75 Düsseldorf: VDI-Verlag, 1981 lools

10 Synthesis of schematic descriptions in mechanieal design

11 An approach to compositional synthesis of mechanical design concepts using computers

12 Synthesis based on function-means trees: Schemebuilder

13 Design processes and context for the support of design synthesis

16 Design patterns and creative design

17 FAMING: supporting innovative design using adaptation - a description of the approach, implementation, illustrative example and evaluation

18 Transforming behavioural and physical representations of mechanical designs

19 Automatie synthesis of both the topology and numerical parameters for complex structures using genetic programming

TRll, the Altshullerian approach to solving innovation problems

In today's socio-economic landscape, companies face the dual challenge of reducing time-to-market while enhancing their innovation capabilities However, this goal is complicated by the inherent uncertainty of human creativity and the unpredictable nature of new product development Systemic theory suggests that companies should adopt a broader perspective, utilizing a systemic time/level reference to better anticipate the evolution of technical systems Numerous studies have explored the development of techniques, often supported by formalized laws, while Altshuller's innovation theory provides a deeper understanding of these principles This chapter presents an overview of TRIZ (the theory of inventive problem solving) from both methodological and structural viewpoints, highlighting its potential integration with contemporary Western methodologies.

The genesis of a theory

Traditional design methods rely on the innate creativity of individuals, where ideas are generated through problem reformulation and analysis While these methods create conducive environments for idea generation, the breakthrough moments of creativity ultimately stem from individuals The TRIZ methodology enhances this intrinsic creativity by providing structured guidance, transforming problems into models that lead to generic solutions tailored to specific contexts This process begins with reformulating the problem, progressing to solution models, and finally allowing designers to apply their creative skills to develop concrete solutions that align with industrial realities.

A Chakrabarti (ed.), Engineering Design Synthesis © Springer-Verlag London 2002

Fig 9.1 Solving a problem using TRIZ

Traditional problem-solving methods often rely on trial-and-error, which can be time-consuming, especially for complex issues TRIZ, a theory designed to combat the blank-page syndrome, provides a structured approach that guides designers in a focused direction By utilizing a systematic process, TRIZ introduces tools at each stage of the solution-finding journey, helping to navigate similar problem configurations that others have encountered This approach quickly reveals two significant advantages: enhanced efficiency and a more directed path to solutions.

The analyses overlook the industry of origin, resulting in a transdisciplinary approach that significantly enhances the chances of discovering solutions by exploring different domains For instance, a chemical industry solution can address a mechanical issue, such as utilizing chemical effects on cavity surfaces of plastic injection tools to achieve a marbled surface finish on molded parts.

The article discusses fundamental principles and various effects, such as Archimedes' principle, the Coanda effect, and the Seebeck effect, as highlighted in specialized literature Notably, the Seebeck effect has practical applications, including the use of heat generated by a domestic oven to produce electricity for household use.

9.1.2 Altshuller: evaluation of a life dedicated to others

A life devoted to design progress is often inseparable from the influential contributions of its pioneer, Altshuller Despite the significance of his work in shaping TRIZ, there are limited publications that chronicle his life through the critical phases of its development In this article, we aim to pay tribute to his enduring legacy.

An approach to c1assifying Altshuller's work

9.1.3 Opening to the West gives TRIZ the opportunity to develop

Altshuller's work on TRIZ was often regarded as "behind the scenes" due to its informal nature, as the Soviet system failed to recognize its fundamental value Many believe that TRIZ reached its full potential only after moving to the West, where the development of associated computer tools and enhanced communication significantly accelerated its progress.

9.2 An approach to classifying Altshuller's work

TRIZ is closely associated with patent analysis; however, a comprehensive examination of its history and Altshuller's life reveals that patents only provide a limited perspective of his contributions Figure 9.2 offers a concise overview of the diverse fields anticipated by Altshuller, along with a precise classification of his referenced and recognized outcomes.

Analysis of inventiveness :ằ Resources of solutions

This article explores the psychological principles behind the design and use of tools, emphasizing how understanding these laws can prevent behavioral inertia in miniature men It delves into the biographies of inventors and their creative processes, highlighting the importance of alternative systems in fostering innovation Additionally, it examines the critical factors of size, time, and cost in the development and application of these tools, providing insights into effective operator strategies.

Analysis of technical system system evolution's history :ằ V epoles & Standards evolution :ằ Matrix for solving

I I technical contradictions methods and lOols Solving tools :ằ Methods for solving physical contradictions

Analysis of scientific and :ằ ARIZ technicalliterature r :ằ Data base of scientific effects

Fig.9.2 Proposed classification of Altshuller's work

Altshuller emphasized key concepts in TRIZ that are crucial for effective idea generation and problem-solving To navigate complex challenges successfully, it's important to understand these principles and adhere to specific guidelines that help avoid common obstacles, such as the "blank-page" syndrome and the complacency of settling for compromise solutions The core ideas presented by Altshuller are thoroughly analyzed in TRIZ, serving as valuable "hot lines" for reflection Keeping these concepts in mind throughout a project's lifecycle can enhance efficiency and relevance in reaching optimal solutions.

The concept of contradiction is central to TRIZ, emphasizing that effective problem-solving requires a thorough analysis to uncover inherent contradictions within issues To address any problem, it is essential to reformulate it in a way that clearly highlights these contradictions Altshuller identifies three distinct types of contradictions that can arise during this process.

• organisational (the initial vision of the problem) - this is vague and does not help us find the right direction towards a solution;

• technical (the first level of detail) - this sets two parameters linked to the same object (or system) in correlative opposition;

• physical (the ultimate level) - this offers a key parameter to the problem, which must subsist in two diametrically opposed states (values)

• The notion of psychological inertia: this is the main obstade to creativity - in TRIZ, tools have been formalised to overcome this hurdle

The concept of the final ideal result suggests that all situations and systems can be understood through the lens of ideality By adhering to specific recommendations that clarify this ideal, we move closer to formalizing solutions Altshuller posits that embracing the idea of ideality involves reducing a system's cost and harmful functions while maximizing its useful functions.

9.2.3 Spotting Altshuller's original idea: the laws (or regularities) of developing technical systems

Altshuller defined a law as a logical trend in development that must either be followed or breached, with the latter often posing risks The analysis and formalization of these laws are fundamental to TRIZ, emphasizing that new products emerge from the accumulation of human knowledge Understanding this developmental logic aids designers in identifying optimal solutions and enhances their creative capabilities Altshuller categorized the development laws for technical systems into three types: static, cinematic, and dynamic.

The static laws give a motionless vision of the system at a given instant t Their purpose is to check the structural and functional wholeness of the system

Law 1: wholeness of parts For a system to ensure its main function, it must have four fundamental parts ideally fulfilling their role in the functioning of the system These four main parts are:

• the driving force (engine), whose function is to generate the energy required to ensure the main function;

• the element of transmission (transmission), which will channel this energy towards the working element;

• the working element (work), which, within the limits of the system under study, will ensure the physical contact between our system and the physical element it acts upon;

• the control element (control), whose main function is to react to the variations in the functioning of the system by adapting automatically to its form, structure and informational output

The corollaries to this law are as follows:

• each element must participate fully in the good working order of the system;

• at least one of the parts must be controllable to adapt to the variations of the control element

Figure 9.3 illustrates Law 1, highlighting the interconnections among the system's components while also defining the physical boundaries of the system being analyzed.

Law 2: conductible energy flow One condition that is essential to the functioning of a system is the free and efficient circulation of energy through its four main parts Furthermore, all technical systems act like apower converter Consequently, the energy must be transferred faithfully without any loss of driving force via the trans- mission to the working and control parts The transmission of energy from one part to another may be material (camshaft, gearwheel, lever, fluid, gas, etc.), a field (mag- netic, electric, thermal) or a combination of the two

Evaluating energy losses by comparing the input energy generated by the driving force to the output energy provided by the working element is crucial for determining compliance with the second law of thermodynamics.

Law 3: coordination of the rhythm of the different parts An essential condition for the optimised functioning of a system consists in establishing coordination in the rhythm (frequency, vibrations, periodicity, resonance) of all the parts Any discrep- ancy between the functioning rhythm of one part and that of another inevitably gen- erates a loss of efficiency that is harmful to the overall performance of the system Thus, it is important to set up a form of harmony between the parts (or their com-

The diagram in Fig 9.3 illustrates Law 1, highlighting the importance of efficient functioning among system components However, when the coordination among these parts is latent, it can lead to suboptimal performance In such cases, the goal shifts towards addressing the discordance in the functioning rhythm of the system's components.

The cinematic laws dictate that the system is analyzed within a comprehensive time-space framework This analysis extends beyond current observations, reaching back to earlier stages to identify any discrepancies with these laws.

Law 4: increase in ideality The development of any technical system strives to attain the highest level of perfection (ideal) By definition, an ideal technical system is a system where the weight, volume and surface area are reduced to the minimum (or even disappear altogether) without changing the working capacity In other words, an ideal technical system is a virtual system that retains and fulfils its own specific functions In practice, systems develop towards the ideal when their func- tional performance improves, while their costs diminish

TRIZ's contribution to integration in the design process

This section compares three theories for integrating TRIZ into various design methods, guided by the intuitive design model, which highlights four key activities of designers: Collect, Create, Construct, and Produce The goal is not to advocate for any specific approach but to illustrate that each theory has its own advantages and disadvantages, making it difficult to choose a definitive option.

9.3.1 Using TRIZ in an approach consisting of applying aseries of tools

Several articles (especially in the USA) have been published on this subject [17,18] Integration in aseries of tools (Figure 9.7a) offers two advantages: benefiting from a b

TRIZ can be utilized as a series of tools or as a meta-method, enhancing existing methodologies by integrating complementary tools This approach broadens the project's scope, pushing beyond the conventional design habits of a single method However, this logical integration may also present certain drawbacks.

• the need to design interfaces between methods;

• the increased complexity of the learning process;

• a longer time span for the project

Integrating TRIZ as the foundational method for a project allows for the incorporation of strengths from other methodologies, despite the inherent limitations and drawbacks associated with TRIZ This integration provides a structured approach, ensuring consistency and clarity by adhering to a specific method, which helps eliminate the confusion that can arise from switching between different methodologies.

9.3.3 TRIZ as a component part of an existing method

Incorporating the strengths of TRIZ during the creation phase can enhance projects utilizing other methodologies, such as value engineering (VE) By integrating TRIZ tools into phases 3 and 4 of VE, the overall relevance and effectiveness of the project can be significantly improved.

The advantages of this integration are twofold

Value Engineering (VE) is a popular method utilized in both industry and education due to its structured approach This structured nature offers a functional orientation to projects, addressing the potential shortcomings often found in TRIZ methodologies.

• The amount of training required as a result of this integration could be low, insofar as only some TRIZ tools have been applied

The only drawbacks to this type of integration are:

• integration does not reach the maximum potential inherent in combining methods;

• all designers who have not previously used a specific method (excepting a per- sonal method) must make substantial efforts in terms of training

9.3.4 The intuitive design model approach to methodological integration

In conclusion, none of the three approaches fully satisfy the criteria of relevance and ease of integration To achieve optimal relevance in the integration strategy, it is essential to consider the existing expertise of the company's designers from the outset.

This conclusion opens a gateway to reftections on the definition of a generic inte- gration strategy specific to a given company

The four phases—Collect, Create, Construct, and Produce—serve as a foundational framework for our studies, as illustrated in Figure 9.7a-c These phases are intentionally generic, offering a flexible structural approach to projects rather than a rigid format This abstraction phase allows us to formulate hypotheses regarding the strengths associated with various methods and to connect these strengths across different approaches.

Companies must recognize that no method fully considers their methodological history, as their structure is inherently fixed Consequently, any organization adopting a new method or set of rules is required to either undergo training to understand the new approach or intuitively adapt it to fit their existing framework for successful integration.

Our analysis is grounded in a prior survey of existing methodologies, which informs the development of an integration strategy tailored to the company We conclude that designers can enhance project relevance with minimal changes to their design practices To achieve this, we propose identifying the strengths of various methods to address any relevance gaps in the project, focusing on integrating only the most effective elements rather than adopting an entire method Once we formalize the strengths of design methods and consider the company's existing methodological and technical knowledge, we can determine the most suitable intuitive design method for the organization.

Here is a summary of the key points in our approach:

1 avoiding straying too far from design habits;

2 maximum use of latent knowledge;

3 minimising efforts in skill-building;

4 fostering the acquisition of the methods' strong points;

5 taking stock of the methodologies without preconceived ideas;

6 drawing up a development plan for the design activity based on an accurate data summary

9.4 Potential development of the theory in research

On the basis of an in-depth analysis of current activities linked to TRIZ around the world, there are three major areas for future contributions

9.4.1 Contributions to integrating TRIZ in one or more existing methods

TRIZ excels in the creative phase of design, a focus often overlooked by traditional Western methods such as Value Engineering (VE), Quality Function Deployment (QFD), Design for Manufacture (DFM), and others By integrating TRIZ with these methodologies, we can enhance their effectiveness, particularly in systematic solution-seeking during the creative process For instance, while QFD may require compromises, TRIZ offers a way to address underlying contradictions, thus fostering innovative solutions and improving overall design efficiency.

9.4.2 Contributions to the development of TRIZ itself

TRIZ, originally developed in the context of the ex-USSR's industrial, scientific, and political landscape, faces challenges when applied in the West due to inherent inconsistencies To fully harness its potential, it is essential to adapt TRIZ to align with Western realities, particularly by revising the modeling of substances-field (Vepoles) and enhancing its graphical formalism Additionally, the theory currently lacks robust concept evaluation, making the formalization of a relevance matrix crucial By incorporating cognitive and economic data, this matrix can significantly enhance the relevance and applicability of TRIZ in contemporary contexts.

Currently, TRIZ appears to be a fully developed tool, particularly due to its operationalization and various computer versions However, conversations with contributors from the former Soviet bloc reveal that this perception is misleading Ongoing work on its foundational principles and standards is closely related to research focused on effectively leveraging knowledge.

9.4.3 Contributions to other fields of activity

Recent advancements in research laboratories from the former Soviet bloc have led to the application of Altshuller's principles across various industrial disciplines, including marketing, management, publicity, politics, and education This work aims to enhance research in these specific areas by utilizing TRIZ as a theoretical foundation to challenge established beliefs Central to this inquiry is the concept of contradiction, which often underlies the questioning process.

9.S Orchestrating the work in Altshuller's wake

The death of TRIZ's founder on September 24, 1998, has led to both positive and negative developments within the theory, resulting in a complex landscape of TRIZ derivatives While the diversity of TRIZ advancements across different countries enriches the discourse, it also contributes to confusion, particularly for newcomers trying to understand the theory A potential solution lies in the establishment of the world TRIZ association (MATRIZ) in Petrosavodsk, Russia, which aims to unite various international associations This initiative focuses on sharing experiences and insights from practitioners worldwide, while also drawing on the foundational perspectives of those closest to Altshuller to help validate and guide the theory's evolution.

Three "developmentalist" visions linked to TRIZ should be noted

The SIT vision, developed in Israel in collaboration with the Ford group, aims to simplify the TRIZ theory by retaining its essential elements while eliminating unnecessary complexities This approach seeks to communicate the core knowledge of TRIZ to a broad audience, enabling more individuals to leverage its significant potential for innovation and problem-solving.