generating a bill of materials
Báo cáo khoa học: "Generating a Table-of-Contents" pptx
Ngày tải lên :
17/03/2014, 04:20
... human evaluations Thanks to Michael Collins, Benjamin Snyder, Igor Malioutov, Jacob Eisenstein, Nina Wacholder, David K Evans, and Judith Klavans 2001 Automatic identification and organization of ... summarization workshop, pages 1–8 Noemie Elhadad and Kathleen R McKeown 2001 Towards generating patient specific summaries of medical articles In Proceedings of NAACL Workshop on Automatic Summarization, ... essential to generate an entire table -of- contents tree in a concerted fashion This paper presents a hierarchical discriminative approach for table -of- contents generation Figure shows a fragment of a...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 65 potx
Ngày tải lên :
03/07/2014, 20:20
... experimental data available for calibration Additional experimental results should allow for better calibration and will pave the way for incorporation and assessment of many of the above phenomena Although ... represented in a Haigh diagram, the material is intolerant to small amounts of damage For initial defects or service induced damage such as FOD equivalent to a crack of 50 m or greater, that damage would ... this behavior of the model can qualitatively predict the experimental observations of Suhr [6] In this work, a 12% CrNiMo blading alloy was cycled at a mean strain of 0.01 and variable alternating...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 1 docx
Ngày tải lên :
03/07/2014, 20:20
... Modeling of Contact Stresses 542 Bence B Bartha, Narayan K Sundaram and Thomas N Farris G Experimental and Analytical Simulation of FOD 558 Jeffrey Calcaterra H FOD in JSSG I Computation of High ... Fatigue A Mechanics of Materials Perspective This page intentionally left blank High Cycle Fatigue A Mechanics of Materials Perspective Theodore Nicholas Air Force Institute of Technology Department ... 6.8.2 Analytical solutions 6.9 Role of slip amplitude 6.10 Stress-at -a- point approaches 6.11 Fracture mechanics approaches 6.12 A combined stress and K approach 6.13 Comparison of fretting-fatigue...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 2 pps
Ngày tải lên :
03/07/2014, 20:20
... data obtained and trends in HCF behavior were felt to be rather generic and applicable to other materials The advantage of the use of a single model material was the ability to generate a large ... effort was materials; particularly the damage tolerant aspects as related to HCF What came out early in the program planning stages was that design for HCF is actually quite straightforward, given ... these authors – Otha Davenport, George Sendeckyj, Major Randall Pollak, Alan Kallmeyer, Bence Bartha, Narayan Sundaram, Thomas Farris, Jeffrey Calcaterra, and Joseph Zuiker – go my sincerest thanks...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 3 docx
Ngày tải lên :
03/07/2014, 20:20
... subsurface at very small pores which are characteristic of this class of materials The crack propagated as a stage I crack along a crystallographic plane before changing to stage II and propagating ... data obtained at a constant value of stress ratio, R For each value of R, a different curve is drawn Many attempts have been made and models developed to consolidate data at different values of ... data at different values of stress ratio, R, and plotting them on, for example, a Goodman diagram as shown above This plot of alternating stress against mean stress is a constant life diagram...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 4 pdf
Ngày tải lên :
03/07/2014, 20:20
... Schematic of damage accumulation applicable to HCF ∗ Figures 1.2 and 1.3, and many variations thereof, were used numerous times as an illustration of how a damage tolerant approach could save ... interval Damage tolerance can be achieved by performing crack growth evaluation as an integral part of detail design of fracture-critical engine components Initial flaws (sharp cracks) should be assumed ... have a minimal fraction of their lives associated with crack propagation For this reason, the Goodman diagram is often used interchangeably as a total or infinite life criterion as well as an...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 5 doc
Ngày tải lên :
03/07/2014, 20:20
... in another special issue [12] A third conference was in Japan in September 2004 A summary of a large amount of experimental data on gigacycle fatigue as well as a description of the test apparatus ... test to another and appears in the resultant database as the constant under which the test was conducted It was probably this type of thinking and the number of available parameters that led the ... fatigue behavior The data obtained at 20 kHz are also compared with 60 Hz data obtained on a conventional test machine and again show no difference In this figure, the data at both frequencies at cycle...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 6 pdf
Ngày tải lên :
03/07/2014, 20:20
... vibratory stresses There are often very few data available in this region, and the extrapolation of data from low values of R and the assumption that statistical distributions of data are the same ... are often necessary, the data in Figure 2.16 illustrate that single parameters with which to consolidate data sets are not always viable because the individual groupings of data, at constant mean ... values of mean stress An example of data obtained at several values of mean stress is presented in Figure 2.16 for a SKH51 tool steel [17] While extrapolation and interpolation of data sets are...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 7 ppsx
Ngày tải lên :
03/07/2014, 20:20
... Introduction and Background variability from material to material, scatter in the data, and lack of sufficient data in many cases prevent the fitting of an equation to such data When mean stress values are ... fatigue of metals are revealed.” 2.6 HAIGH DIAGRAM AT ELEVATED TEMPERATURE In the final program on HCF material behavior [27], a Haigh diagram was constructed for a single crystal alloy, PWA 1484 at ... some data are handled by changing the value of w for negative values of R, it can be seen that the Walker equation has the same general characteristics as the SWT equation for negative mean stress,...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 8 ppsx
Ngày tải lên :
03/07/2014, 20:20
... here that margins of safety be imposed on both parameters (alternating stress and maximum stress) in order to insure a safe design The Nicholas–Haigh diagram was an attempt to present data in a form ... the same general trend as the Jasper equation curve of Figure 2.33 for positive mean stresses and have a shape Characterizing Fatigue Limits 59 1.2 Normalized Haigh diagram Jasper equation σalt/σ–1 ... values of R and high frequency can often be above the quasi-static ultimate strength of the material This, in turn, will not produce a smooth plot on a Haigh diagram if a quasi-static ultimate...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 9 docx
Ngày tải lên :
03/07/2014, 20:20
... requires a large database is a Haigh diagram, which requires data at a number of mean stress or stress ratio conditions By early in the 1900s, numerous accelerated tests for endurance limit had been ... instrumentation, computers, and other technical fields have provided the capability to evaluate the long life fatigue behavior of materials far beyond what was envisioned in the late nineteenth and early ... Presence of Naturally Initiated Small Surface Cracks”, Fatigue and Fracture Mechanics: 33rd Volume, ASTM STP 1417, W.G Reuter and R.S Piascik, eds, American Society for Testing and Materials, West...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 10 ppt
Ngày tải lên :
03/07/2014, 20:20
... Introduction and Background Validation of the step-test procedure Data for a Haigh diagram were obtained using the step-loading procedure for both the bar and plate forms of Ti-6Al-4V [21] The data are ... The data obtained at R = are of particular interest in the evaluation of the validity of the step-loading procedure In an investigation on the bar material, Morrissey et al [29] noted that at high ... cycling at stress ratios higher than approximately 0.7 leads to strain accumulation Micrographs of the fracture surface at various magnifications taken with a scanning electron microscope (SEM) are...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 11 potx
Ngày tải lên :
03/07/2014, 20:20
... Statistical analysis Data from staircase tests can be analyzed statistically by assuming any type of statistical distribution for the percent failure data Normal and Weibull distributions are ... time that the fatigue life of a metal at a given stress varies statistically ∗ and more recently it was discovered, in this laboratory, that the endurance limit is also a statistical quantity and ... observations [35] Another great advantage to the method is that the statistical analysis is quite simple under certain conditions Many advances in statistical analysis of data come from the field of biology...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 12 docx
Ngày tải lên :
03/07/2014, 20:20
... normally A hypothetical material having a median FLS of 50 and a standard deviation of was chosen The mean value is an arbitrary unit for this material, only the standard deviation, s, is of importance ... the mean value of FLS as well as the variance Having this information available in advance, such as from extrapolated LCF test data, will help in choosing a starting value as well as a stress ... staircase sequence Additional test data may be required, at lower stresses if the majority of the data are failures, or at higher stresses if most of the data are survivals The mathematics of...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 13 doc
Ngày tải lên :
03/07/2014, 20:20
... estimation technique to analyze the randomly generated staircase data, showed that the mean value of the RFL was well predicted for small numbers of tests ranging from a total of 10 to a total of ... orders of magnitude The RFL model, which contains parameters, requires substantial data over a range of stress levels and lives to accurately estimate the parameters Using Bayesian methods, the analysis ... used, both the √ staircase and the ArcSin P method underestimate the standard deviation of the FLS [39] From observations of a number of numerical simulations, Braam and van der Zwaag [39] developed...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 14 docx
Ngày tải lên :
03/07/2014, 20:20
... Finally, the RFL model was applied to a combination of the LCF data and the staircase test data, where cycles to failure in the failed staircase tests were used as part of the database A summary ... anomalous behavior was attributed to a combination of material scatter, possible variances in batches of material preparation/machining, and the possibility of a coaxing phenomenon in this material ... development and analysis described in the section above, a SWT and a equiv parameter are used to consolidate data obtained at various stress ratios in order to provide a larger database The vertical axis...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 15 ppsx
Ngày tải lên :
03/07/2014, 20:20
... can be employed Using a commercial software package called Minitab, the data were evaluated assuming a normal fit to log life as was the case for the real data [58] The results of that evaluation ... a Haigh diagram by using an equation to represent behavior at all values of mean stress or stress ratio, but data for at least one value of R are needed to establish the constants Uniaxial fatigue ... ratio, R, there are many cases in design where data at a single value of R = −1, fully reversed loading with zero mean stress, are the only data available Such data, often obtained from vibratory...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 16 pdf
Ngày tải lên :
03/07/2014, 20:20
... for crack propagation when damage can be characterized in terms of an actual fatigue crack Damage can be in the form of any loading or service event that degrades the properties of a material, ... Testing and Materials, 1963, pp 12–13 √ 39 Braam, J.J and van der Zwaag, S., A Statistical Evaluation of the Staircase and the ArcSin P Methods for Determining the Fatigue Limit”, Journal of Testing ... Physical Basis of Metal Fatigue, Blackie & Son Ltd, London, 1969 12 Maennig, W.-W., “Planning and Evaluation of Fatigue Tests”, ASM Handbook, Volume 19, Fatigue and Fracture, ASM International, Materials...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 17 pptx
Ngày tải lên :
03/07/2014, 20:20
... specimen Of particular significance in using the Kitagawa diagram for any geometry is that the endurance limit and the value of a0 for the short crack correction are not material constants but, rather, ... Kth LC a Y a a + a0 Y a + a (4.7) where, as in the calculation for a0 , the Y terms can usually be ignored The significance of the Kitagawa diagram with the short crack correction is that it shows, ... lengths less than that of point D may initiate and arrest, these crack lengths are generally very small (the so-called small crack or short crack) and not detectable other than in a laboratory setting...
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High Cycle Fatigue: A Mechanics of Materials Perspective part 18 ppsx
Ngày tải lên :
03/07/2014, 20:20
... loading and is referred to as an overload effect, where prior cracking at a high load level tends to retard crack extension at lower loads To analyze the experimental data, a Kitagawa diagram ... parameter when assessing potential material degradation from fretting fatigue Overall, the Kitagawa diagram, using the El Haddad transition modification, provides a reasonable representation of ... KA = KB = mA x a = 2 a x mB x a = a x (4.17) x mB (4.18) a + M 1A − a dx c a dx x a c x mA x a x a + M1B 1/2 x a + M 2A − 1/2 + M2B x x + M 3A − a a x x + M3B a a 3/2 (4.19) 3/2 (4.20) In evaluating...
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