Pro/DESKTOP® Tutorial Rescue Craft – Density Written by Tim Brotherhood Copyright © 2003, Parametric Technology Corporation (PTC) All rights reserved under copyright laws of the United States and other countries PTC, the PTC Logo, The Product Development Company, Create Collaborate Control, Simple Powerful Connected, Pro/ENGINEER, Pro/DESKTOP, Wildfire, Windchill, and all PTC product names and logos are trademarks or registered trademarks of PTC and/or its subsidiaries in the United States and in other countries All other product names and marks referenced herein are trademarks or registered trademarks of their respective holders Conditions of use Copying and use of these materials is authorized only in the schools of teachers who attend official training with a PTC certified trainer All other use is prohibited unless written permission is obtained from the copyright holder Acknowledgements Sheila Schencke, Executive Director, STARBASE Louisiana Barbara Koscak, Executive Director, STARBASE Michigan Rick Simms, Deputy Director, STARBASE Michigan Feedback In order to ensure these materials are of the highest quality, users are asked to report errors to PTC at schools@ptc.com Suggestions for improvements and other activities would also be very welcome Rescue Craft T ABLE OF CONTENTS FILES FOR RESCUE CRAFT INTRODUCTION Loft through profiles .7 Rescue shuttle Features browser .8 Creating a loft 11 Measuring complex solids 17 MEASUREMENTS 18 Center of gravity 18 Final assembly 19 BROWSER 20 EXTENSION W ORK 21 Rescue Craft FILES FOR R ESCUE CRAFT The following files will be needed to successfully complete this project: File Name Escape capsule fuselage.des Escape shuttle assembly.des Tail fin.des Rescue Craft I NTRODUCTION Since Uri Gagarin became the first person to orbit the earth many others have ventured into space There have been few accidents but some have lost their lives including astronauts in ground tests for the first Apollo missions Apollo 13 was nearly lost due to an explosion but they were able to use the Lunar module as lifeboat and return safely to earth Photograph NASA Russia has also had accidents, most recently the Mir space station was severely damaged when a supply craft crashed causing depressurization The 25th flight of the shuttle program failed catastrophically killing all crew members As more people venture into space it is important to plan for potential accidents setting up contingency plans to reduce the risk of serious injury or loss of life Photograph NASA The international space station is a joint project with agencies on several continents Co-operation on a scale never seen before is creating the largest permanently manned space station ever planned Astronauts will live and work on the station carrying out experiments in the micro gravity environment space provides Illustration - Maris Mutimedia – Space Station CDROM Rescue Craft Should a major problem occur astronauts and scientists are able to use a Russian Soyuz craft as a lifeboat It is permanently docked and ready for immediate use when needed Illustration - Maris Mutimedia Space Station CDROM Designing a capsule for re-entry through the atmosphere of a planet has very strict design constraints Some of these include: • Operation in a space environment • Recovery • Re-entry through the upper atmosphere • Control in al phases • Descent through the lower atmosphere • Life support • Landing Modeling complex shapes CAD software can help greatly when developing the shape of components For complex curved surfaces the extrude and project features in Pro/DESKTOP are limiting This tutorial will show you how to create shapes with complex curves using the powerful sweep and loft tools You will also use some of the measurement tools available in Pro/DESKTOP Rescue Craft Loft through profiles Rules Lofting requires two or more valid profile sketches Pro/DESKTOP then creates a solid object between the profiles Loft Three profile sketches on offset workplanes for a small boat hull The solid shapes produced by lofting between the three profiles The sketches not have to be parallel and lofting can create a closed shape The following example is taken from the Pro/DESKTOP Help tutorials This tutorial will show you how to create the vertical stabilizer for a rescue shuttle using the loft feature First lets have a close look at how the fuselage was created Rescue Craft Rescue shuttle • Open the file called Escape capsule fuselage.des Only two main features determine the overall shape The fuselage is lofted and extrude is used to create the wings To give you an idea of how the features work let's look at the sketches that make up the loft We can this through the browser but listing features • Change the browser to show features Features browser The features section of the browser stores a history of all 3D operations The loft feature is named Fuselage and is second in the list • Expand the Fuselage feature by clicking on the + sign next to the loft icon You will now see the sketches that were used to create the loft feature They are the same sketches you can view through the Workplanes view of the browser Selecting lines from the browser • Move the mouse over the sketch named Center Cargo and right mouse click • From the floating menu, click on Select Lines Rescue Craft All lines on that sketch will be selected They are easily visible as red lines in the design window • Repeat these steps to see which lines are on each of the sketches making up the lofted fuselage Lofting explained • Move the mouse over the loft icon and right mouse click • From the floating menu select Redefine The Loft profiles dialog window will open The sketches making up the loft will be listed and notice they are in the same order in the browser Rescue Craft • In the list of sketches in the window click on the one named Center cargo Look in the design window The sketch will have a small yellow 'handle' on it • Click on a different sketch name in the list The small yellow handle will move to the highlighted sketch The yellow handle shows which corner or vertex will be joined when the shape is lofted Pro/DESKTOP draws a loft line between the vertices Loft lines To explain the following examples a loft has been created between two hexagons The first pair of illustrations shows a loft line between aligned corners of the hexagons The resulting loft looks identical to an extrusion Using exactly the same sketches but moving one of the loft handles to the adjacent vertex creates a twisted loft Rescue Craft 10 Creating a loft This section takes you through creating the vertical stabilizer (tail fin) using a loft The finished vertical stabilizer will look something like this when complete There are four sketches on angled workplanes for the lofted shape making the largest part of the fin Loft Fin Below this is a small extruded piece for the connection with the fuselage Lastly, a circle is projected up the rear of the shape creating the cylindrical surface for the rudder hinge • Extrude base Project hinge Open the file called Tail fin.des The extruded base has been done for you The next step is to create the loft above this The Base extrusion sketch is identical to the one we need for the base of the loft so we can use it again The next step is to create a new workplane inclined at 30 degrees to the base To make this possible, a short construction line was drawn on the Base extrusion sketch passing through the origin to act as a hinge Rescue Craft 11 New angled workplane • Open the Workplane pull-down menu and select New Workplane • Fill-in the name as 30 degree • Select the Angled option • Type in 30 for the Angle The hinge line must be selected manually • Open the roll-down menu and click on Lines • Leave the New Workplane dialog window open • Move the mouse over the short hinge line and click to select it The new workplane will preview Notice there is a small yellow handle on the edge of the new workplane With this it is possible to adjust the angle by dragging Leave it at 30 degrees • Click on When a workplane is created in this way it is empty A new sketch will be needed New sketch • In the Workplanes browser move the mouse over the name for the new workplane and right click • From the floating menu select New Sketch… • Type the name 30 degree for the sketch Rescue Craft 12 • Click on Before copying the lines it will be easier if the origin arrows are rotated to match the direction in the base loft sketch Before transforming the origin arrows After transformation Rotating the origin arrows • Open the Workplane pull-down menu • Select Transform Axes • Click on the Rotate tab • Type in 270 for the angle of rotation (Pro/DESKTOP measures angle counterclockwise) • Click on Copy sketch lines • Make sure the browser is showing Workplanes • Click on the + next to the Base workplane to expand it • If the sketch called Base extrusion is not active double click to activate it • With the mouse cursor over the sketch and right click • From the floating menu click on Select Lines • Open the Edit pull-down menu and select Copy The lines are now stored on the Windows clipboard • From the Edit pull-down menu select Paste The sketch lines are pasted into the new sketch 60 degree workplane Create another angled workplane at 60 degrees from the base workplane Add a sketch to the new 60 degree workplane If necessary, change the orientation of the origin arrows Copy the lines from the Base extrusion sketch onto the new sketch Rescue Craft 13 Lateral sketch • Create the fourth and final sketch needed for the loft on the Lateral workplane and name it Lateral loft • Change the orientation of the axes • Copy the same set of lines onto the new sketch If we lofted the sketches as they are, the solid would be the same shape as a revolved profile The required shape for the fin is outlined by construction lines on the Side profile sketch on the Frontal workplane To achieve this shape, we will alter the length of each sketch • View Onto Workplane (Shift + W) • Autoscale (Shift + A) We need to fix part of the sketch to make sure it changes size in the correct direction • Select the bottom line of the profile • Open the Constraint pull-down menu and click on Toggle Fixed fix • Create a dimension constraint for the vertical length of the rectangle Tip: Remember to use the attraction point for center when locating the top end of the constraint • Change the constrain to a value of 5300mm Rescue Craft 14 The sketches should be these lengths 5300mm 6000mm 4500mm Change the length of the sketches on the two angled workplanes to these values Loft the tail fin The loft tool does not appear in the default features toolbar • Open the Feature pull-down menu • Select Loft Through Profiles The Loft Profiles dialog window opens • In the design window click on a line in each sketch to add them to the list Rescue Craft 15 The loft line connects a vertex in each sketch It is unlikely these will be located in the correct place Moving vertices • In the Loft Profiles dialog window select one of the sketches • A yellow vertex handle will appear somewhere along the sketch lines The lines are cluttered at the bottom right of the view so to make it easier to position the handles we will locate them towards the front of the fin • Drag the handle to a position near the curved at the front of the sketch • Click on another sketch in the dialog window and move the handle • Repeat for the remaining sketches • Click on loft to complete the The last step is to create a cylindrical surface at the rear of the fin for the rudder hinge • On the Base workplane create a new sketch called Hinge • Draw a circle at the location shown in the diagram on the right Use attraction points to constrain the circle to center and ends of the existing line Rescue Craft 16 Project hinge profile • Select • Change the options to Subtract material and Thru entire part • Click on , the Project Profile tool The fin is now complete • Remember to save your work Now we can look at some of the measurements Pro/DESKTOP does on solid shapes Measuring complex solids Pro/DESKTOP calculates many other variables for components including the mass based on the density of the material We will look at the tail fin assuming it will be made out of carbon fiber composite material Setting the density • Open the Tail fin finished.des component in Pro/DESKTOP • Open the Tools pull-down menu • Select Variables Rescue Craft 17 • In the dialog window click on , the component symbol, in left panel You will see density listed in the right hand panel It is currently set to the density for water but in slightly strange units of Kg m-3 You need to change this to the density for carbon fiber • Click on the value column and change the number to 0.000002267 Close the dialog window MEASUREMENTS • Open the Tools pull-down menu • Click on Select New Measurement • From the fly out menu click on Mass Properties A dialog window will open Drag the window to one side of the screen until you can see the component and the dialog window Center of gravity The first thing you will notice is the red dot and green arrows that have appeared in the design window These show the location of the center of gravity for the component In the Mass properties dialog window you will also see the x, y and z numerical values for the C of G The dialog window contains other useful information For each measurement try to think of practical uses for the information Rescue Craft 18 Surface area This is measured in mm3 Think about the quantities of materials, surface finishes and heat Volume This is measured in mm3 Consideration of materials may help you think of uses for this measurement Mass Measured in Kg, you should have no problem thinking of practical uses for this measurement Final assembly • Open the file Escape shuttle assembly.des • Open the Assembly pull-down menu • Locate and select the Tail fin.des component and click on Create assembly constraints between the surfaces shown below Center axes Mate Mate A mate (offset) already exists between the rudder and the fuselage • Add a Center axis assembly constraint between the fin and rudder The assembly is complete • Save the assembled model Rescue Craft 19 BROWSER The browser provides a comprehensive history of the steps taken to create a model and the order they are carried out It is also possible to step through the features 're-creating' the model The next section shows how • First, use the Select part tool and highlight the fuselage • Right click and from the floating menu select Open file in context Finish flag This is the checkered flag symbol, usually found at the bottom of the browser • Make sure the browser is showing Features • Using the mouse, click and drag the finish flag to the top of the list of features The flag will reposition above the Nose feature • Update the design , and the solids will disappear The finish flag will appear at the top of the list of features in the browser The model may disappear completely from the design window Pro/DESKTOP hides information depending which selection tool is active The sketches are still there • Click on the line select tool The sketches that make up the model should now be visible Tip: Moving the finish flag and saving the file is an excellent way to compress files before saving and sending them via email The fuselage file compressed in this way is 38kB when saved When the updated file is saved with the finish flag at the bottom of the browser the file size is a massive 3.1Mb! Before looking at the browser in more detail we will look briefly at the sketches that make up the lofted fuselage Rescue Craft 20 EXTENSION W ORK • Shell the fin from the bottom surface then make new mass measurements to see the reduction in mass Work out the saving in launch costs based on $22,000 per Kilogram • The density figure we have provided is for pure carbon What is the value for carbon fiber/ epoxy resin composite material? • Why is a composite material used instead of pure carbon? • Research the density/ strength of different materials Is there a lighter material the fin could be made from? Is it as strong as carbon fiber? Rescue Craft 21