Module CE4 GM4-MIQ4-PL4

Travaux Pratiques n°6 CAO Advanced Simulation With Mechanism and Mechanica

¾ Part 1 : Transferring mechanism loads to Mechanica ¾ Part 2 : Sensitivity and Optimization Studies ¾ Part 3 : Thermal Finite Element Analysis ¾ Part 4 : From Mechanism Studies to Mechanica

Module CE4 GM4-MIQ4-PL4 CONTENTS Part 1 : Transferring mechanism loads to Mechanica I. Introduction II. Assign Mass Properties III. Assign Friction Properties to all Joints IV. Define a Force Motor V. Motion Analysis VI. Seeing the Results VII. Transfer the resultant loads into Mechanica VIII. Review Part 2 : Sensitivity and Optimization Studies I. I. Introduction II. Defining Boundary Conditions III. Defining Materials IV. Running a Static Analysis V. Creation of the design variable VI. Local Sensitivity Study VII. Global Sensitivity Design Study VIII. Optimization Design Study IX. Review Part 3 : Thermal Finite Element Analysis I. Introduction II. Starting a Thermal Analysis III. Defining Thermal Loads IV. Defining Boundary Conditions V. Defining Materials VI. Running an Analysis VII. Seeing the Results VIII. Additional Analysis IX. Combining Analyses X. Review Part 4 : From Mechanism Studies to Mechanica I Introduction II. Setup the Load Transfer to Structure PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 III. Setup lever.prt for Structural Analysis IV. Run the Structural Analysis

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PART 1 Transferring mechanism loads to Mechanica I. Introduction In this tutorial, you will run a mechanism analysis to determine the reaction forces on a connecting rod in an engine assembly. Afterwards, you will transfer the maximum forces from the mechanism reaction to Mechanica. The engine have been assembled using joint connections. Then, a servo motor, which turns at 90 deg per sec, have been defined and kinematics analysis have been created. The assembly is composed of several parts. You can download the engine.asm assembly to your working directory ~\TP6\Part1.

Figure°1 – Engine Assembly. • Choose Applications > Mechanism now to take your model into analysis. • To see the motor in operation it is necessary to edit the Run_Engine analysis. When this is done you should be able to press the Run button at which point the motor will run and the mechanism will be flexed through its full range of movement – you should see the movement on the screen.

II. Assign Mass Properties In order to define a dynamic analysis you must assign the mass properties to each part. • To assign the mass properties choose Applications > Standard. Select the part eng_block_rear.prt in the model tree, right-click and click Open. Click Edit > Setup > Mass Props to assign the density. Enter the value for medium cast iron steel i.e 7.7e-9 and click OK > Done. Save the model. • Repeat the previous steps for all of the parts listed in the following table : PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 Part Material Eng_bearing.prt Stainless Steel Eng_block_front.prt Medium Cast Iron Steel Cylinder.prt Medium Cast Iron Steel Crankshaft.prt High Carbon Steel Flywheel.prt High Carbon Steel Piston.prt Aluminium 2014 Piston_pin.prt Chromium Steel Piston_ring.prt Chromium Steel Connecting_rod.prt 4340 Steel Table 1 - Engine Parts Density.

Density 7.744e-9 7.700e-9 7.700e-9 7.468e-9 8.030e-9 2.794e-9 7.700e-9 7.700e-9 7.780e-9

III. Assign Friction Properties to all Joints Now, we can define a mechanism analysis to determine the reaction forces on the connecting rod in an engine assembly • Choose Applications > Mechanism now to take your model into a new analysis. Then pick the pin joint on the axis of the motor (Connection_1.axe_1) to define its settings and right click on Edit Definition. Click the Dynamic properties and click Enable Friction to enable it. Set static friction μs=0.15, kinetic friction μk=0.1 and radius R=0.1. Click OK. • Repeat the previous steps for all of the joints listed in the following table : μs μk R Joint Axis Connection_1 Rotation 0.15 0.1 0.1 Connection_1 Translation 0.15 0.1 Connection_3 Rotation 0.15 0.1 0.1 Connection_5 Rotation 0.15 0.1 0.1 Table 2 – Friction Coefficients.

IV. Define a Force Motor • A force motor can be created using Insert > Force Motors shown.

. The dialog in Figure 2 will be

Figure°2 – Force Motor Dialog. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 • You first have to select the axis of the motor so pick the blue arrow at the axis of the motor. On the profile tab you can define how quickly the motor turns. Enter the value 1 Nm into the A pane below Magnitude. Click OK.

Figure°3 – The Joint Axis of the Motor Force.

V. Motion Analysis • Now choose Insert > Initial Conditions the default settings.

to define the start conditions. Click OK to accept

• To see the motor in operation it is necessary to define an analysis using Analysis > Mechanism . First define the graphical display parameters. Call this analysis Analysis Run_engine_dynamic. Enter the values shown in Figure 4. Also click on the Motors tab and press the button to add the force motor definition to the analysis. Press also button to remove the servo motor definition to the analysis. Make sure gravity and friction are enabled in the Ext Loads tab. • When this is done you should be able to press the Run button at which point the force motor will run and the mechanism will be flexed through its full range of movement – you should see the movement on the screen.

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Figure°4 – Analysis Definition.

VI. Seeing the Results Watching the action on the screen is not very accurate. You may need to know more precisely some value from the mechanism such as how a connection reaction varies over the duration of the dynamic analysis. This is known in ProEngineer as a measure. • To create a measure choose Analysis > Measures . In the dialog choose to create a new measure. Type a name of Rod_bot_X and a type of Connection Reaction picking the Connection_3. Ensure that Component is set to Radial Force. Click OK on the Measure Definition dialog. • Create a second new measure. Type a name of Rod_top_X and a type of Connection Reaction picking the Connection_5. Ensure that Component is set to Radial Force. Click OK on the Measure Definition dialog. • Now highlight the Rod_bot_X and the Rod_top_X measures. Highlight the at the top of the dialog should Run_engine_dynamic result set and the small graph icon activate. Press this icon to see the results.

VII. Transfer the resultant loads into Mechanica • To transfer the resultant loads into Mechanica choose File > Use in Structure. The dialog in Figure 5 will be shown. PLATE-FORME MECANIQUE

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Figure°5 – Transfer Definition. • Select the connecting_rod.prt as the body and the component. Set Evaluate At from Time to Max for all Loads and click Connection_3_Force and Connection_5_Force to transfer the resulting force loads. • We can now open the connecting_rod.prt part and apply resultant load in Mechanica mode by using Insert > Mechanism Load > OK. • Prepare and run a structural analysis in order to calculate the maximum stresses applying on the rod part when the motor turns. Encountering a problem when running this structural analysis? a) You first need to distribute these point forces onto surfaces in the model. b) Then, remember that the part must be isostatic to run a structural analysis, in other words you must suppress the rigid movements of the part. NOTE – How to suppress the rigid movements? In this example the part operating in the mechanism is moving in space. To perform a structural analysis with the loads imported from the mechanism analysis it is thus necessary to install restrictions that maintain the part stationary in space and keep the solver numerically stable. There are several solutions for doing this. 1. You can define some springs connected to the Ground with a very small stiffness. 2. You can tick the “Inertia Relief” option. 3. You can use the symmetry properties of the part and of the loadset (non applicable in this example). 4. You can use a so-called “three-point constraint”. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 For any solution (except for the “Inertia Relief” option) you should apply restrictions so as to not prevent deformations generated by the loadset.

Figure°6 –Von Mises Stress.

VIII. Review So what • • •

should you have learnt? How to define a force motor to a pin joint. How to measure the connection reactions. How to transfer them into a structural analysis.

Any problems with these? Then you should go back through the tutorial – perhaps several times – until you can complete it without any help.

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PART 2 Sensitivity and Optimization Studies I. Introduction Design parameters enable you to designate dimensions and parameters on your model that you may wish to change. Once you have created design parameters, sensibility studies enable you to more fully understand the effects of varying the design parameters on your model. You can use these studies to determine how sensitive a particular quantity, such as Von Mises Stress, is to variations of a particular dimension parameter. In this tutorial, you will learn how to design parameters and studies enable you to determine how sensitive measures such as stress, displacement and mass are to changes in model parameters. A model of a motor is provided for you to work with in this tutorial. This assembly should be downloaded to your working directory ~\TP6\Part2\motor.asm. The single piston motor assembly is a possible alternative to the current engine in a drill assembly. The connecting rod in the motor has not been analyzed for the forces expected during the use of the drill. You will first create a basic static analysis to compute the stress and strain distribution over the connecting rod.

Figure 1 – Motor Assembly • Open the rod.prt in the model tree.

II. Defining Boundary Conditions Task 1 – Define the constraints.

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Module CE4 GM4-MIQ4-PL4 • Choose Applications > Mechanica now to take your model into analysis. Click Continue on the box notifying you of the units of your model. The Model Type dialog should appear. This tutorial covers the structural analysis only. Make sure the Mode option is set to Structure and click OK.

Figure 2 – Constraint Surfaces: from the Mechanica objects toolbar. Enter • Click Insert > Displacement Constraint Fixation as the name and keep ConstraintSet1 as the Member of Set Name. Select the surface as shown in the Figure 2. Ensure that WCS is set as the coordinate system. Fix movement in all directions and click OK. Task 2 – Create a point for applying a directional load. • In standard mode, ensure that Datum Points toolbar to enable their display.

and Coordinate System

• Select the PNT0 datum point in the model tree and select Edit > Copy

are active in the main

. Then click Paste

in the main toolbar. Click Apply Move/Rotate transformations to copies > OK. Special Select the Y-Axis on the DEFAULT_CSYS coordinate system and drag the new point 10 away from rod.prt. Right-click in the graphics window and select New Move, select the X-Axis on the DEFAULT_CSYS coordinate system and the new point 1 away from rod.prt. Click Complete Feature to finish

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Figure 3 – Point PNT2 Task 3 – Define the load.

Figure 4 – Bearing Load • Next define the load on the rod. Within Mechanica, choose Insert > Bearing Load or pick the icon to apply a load over a surface. Click on below Surface(s) in the Bearing dialog then pick the unconstrained hole and middle-click to complete surface selection. Click to edit the Force from Components to Dir Points & Mag. Select PNT0 and PNT2 for the From and To point. Type a value of 50 in the field below Magnitude. Press Preview – the arrows should point the same way as in Figure 4. Click OK in the Bearing dialog to finish.

III. Defining Materials PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 • The final definition for this analysis is the material. Choose Properties > Materials and the Materials dialog will appear. Scroll down the Materials in Library to find AL2014 and double click on it to transfer it to this model. Choose Properties > Materials assignment the rod part and OK to assign the material. Close the material dialog.

and click on

IV. Running a Static Analysis That’s it you are ready to run an analysis. • Choose Analysis > Mechanica Analyses/Studies and the dialog in Figure 5 appears. From this dialog choose File > New Static and type the name Rod_Static and press OK. Notice the METHOD is single pass adaptive. This method is used for quick checks to ensure everything is defined correctly and to get rough results quickly. For more accurate results you would change this to multi pass adaptive. Leave it as it is for now and OK. Choose the icon

to run this analysis

choosing yes for error detection. Press to watch the report of the analysis as it runs. After a few seconds (longer on a slower machine!) the report should state Run Completed. Close the Analyses and design Studies dialog.

Figure°5 – Analyses and Design Studies Dialog • Scroll down the report to view the progress. Look for the maximum Von Mises and principal stresses, maximum displacement, resultant loads, and error estimates. Did the run complete without any errors? Review the Memory and Disk Usage information. Review the elapsed time. Click Close to exit the Summary window. • All results are handled in a separate though integrated module of ProEngineer. Choose Analysis > Results

. The main graphics window will go blank and the menus and icons will all change.

Choose Insert > Result Window or the appears press PLATE-FORME MECANIQUE

icon. In the Result Window Definition dialog that

and click (not double click) on the folder which is the same name as the 13

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Module CE4 GM4-MIQ4-PL4 analysis that is Rod_Static. Enter rod_max_vm as the name of the window and enter Maximum Von Mises Stress as the title. Ensure that the Display type is set to Fringe, that the Quantity is set to display Stress and that the Component is set to Von Mises. Click the Display Options tab and click Continuous Tone to enable the display option. Click OK and SHOW to finish the definition and display the result window. • Click Copy to copy the existing results window. Enter rod_disp as the name of the window. Enter Rod Displacement as the title. Ensure that the Display type is set to Fringe. Click the Quantity and set the quantity to display Displacement. Ensure that the Component is set to Magnitude. Click the Display Options tab and click the Deformed option to enable it and set a scale of 10%.

Figure°5 – Results • Click File > Exit Results > No to close the Mechanica results window.

V. Creation of the design variable • Choose Analysis > Mechanica Analyses/Studies . Choose File > New Sensitivity Design Study. Enter rod_gs as the name of the study. Select rod_static (Static) from the Analysis list. Verify that the type is set to Global sensitivity. • Pick the icon and select Extrude 2 in the model tree. Select the dimension as shown in the Figure 6. Edit the name to rod_thickness. Define the range by editing the minimum to 1 and edit the maximum to 2. • Pick the icon and select Sketch 1 in the model tree, and select the 8 dimension. Edit the name to piston_neck. Define the range by editing the minimum to 3 and edit the maximum to PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 8. • Pick the icon and select Sketch 1 in the model tree, and select the 4 dimension. Edit the name to crank_neck. Define the range by editing the minimum to 3 and edit the maximum to 6. icon and select Round 2 in the model tree, and select the 3 dimension. Edit the • Pick the name to round. Define the range by editing the minimum to 2 and edit the maximum to 4. The reason you are selecting Round 2 only is because Round 2 (2) is a dependent copy of Round 2. Hence when you change Round 2, you are also changing Round 2 (2). • Select all design parameters and enter 4 for number of intervals to generate four models (steps). Click Options > Shape Animate the Model to preview the design range. Enter Yes to proceed to the next step as necessary. Click Yes to return the model to its original shape and Close to close the Design Study options dialog box. • Save the model.

Figure 6 – Design Parameters This completes the definition of design parameters. Please do not close the window or erase any models. After defining design parameters, local and global sensitivity studies are created and run. The effects of varying the design parameters on specific aspects of the model are explored.

VI. Local Sensitivity Study Task 1 – Create and run a local sensitivity study. • Choose Analysis > Mechanica Analyses/Studies . Choose File > New Sensitivity Design Study. Select rod_gs in the Analysis and Design Studies field if necessary. Click Copy > Edit > Analysis/Study …Type rod_ls as the name. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 • Change the type from Global sensitivity to Local Sensitivity. Verify that the variables and their settings match the table below. Click OK. Design Parameter

Value

rod_thickness

1

piston_neck

8

crank_neck

4

round

3

Table 1: Design Parameters • Click Configure Run Settings

.

Click Use Elements from and Existing Study. Ensure that

the rod_static study is selected. Click OK. Choose the

icon to run this analysis choosing yes

for error detection. Press to watch the report of the analysis as it runs. After a few minutes the report should state Run Completed. • Scroll down the report to view the progress. Review the convergence behavior, and information dealing specifically with local sensitivity : ¾ Did the run complete without any errors? ¾ Review the Memory and Disk Usage information. ¾ Review the elapsed time. • Close the Report dialog and the Analyses dialog. Task 2 – Review local results. • In this section, we are going to create three result windows to compare how munch of an effect each of the four parameters is having on maximum Von Mises Stress. to start defining Mechanica results. Do not save the model if • Choose Analysis > Results icon to create a result window definition. prompted. Choose Insert > Result window or the • Enter thickness_stress as the name of the window and Rod Thickness Stress as the title. Ensure that rod_ls and rod_static are listed as the Design Study selections. Ensure that the Display type is set to Graph and the Quantity is set to display Measure. Click Define Measure , select max_stress_vm, and click OK. Ensure the graph is set to rod_thickness. Click OK and Show to finish the definition and display the result window. • Repeat these action and display in the result window four plots shown the evolution of the maximum Von Mises stress with each the design parameters. • Select the Crank_neck graph to activate the results windows. Click the Rod Thickness Stress graph. • Select the Rod Thickness Stress graph to activate the results windows. Click the Piston_neck Stress graph. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 • Select the Piston_neck Stress graph to activate the results windows. Click the Rounds Stress graph.

Figure 7 – Graphical Results from the Local Sensitivity Analysis Review the plots and determine the following informations: ¾ Which parameter has the greatest effect on the maximum von Mises stress? ¾ Which parameter has the least, or perhaps no effect? The following conclusions are made: ¾ The crank neck feature has a big impact on the maximum Von Mises stress. ¾ Rod thickness has less effect. ¾ The piston neck feature near the piston pin and rounds features have little effect on the maximum Von Mises stress. ¾ Since piston neck feature and rounds features have little effect on any quantity of interest, they will be excluded from future studies. However, you may still want to include them in any optimization studies if you are looking to minimize the mass of your part. • Click File > Exit Results > No to close the Mechanica results window.

VII. Global Sensitivity Design Study After defining local sensitivity study, global sensitivity design study are created and run. The effects of the design parameters crank_neck over its range are explored. Hence, you run a global sensitivity study on the crank neck feature to determine how stress and mass are affected by changing its value. Task 1 – Create and run a global sensitivity study. PLATE-FORME MECANIQUE

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• Choose Analysis > Mechanica Analyses/Studies . Choose File > New Sensitivity Design Study. Verify that rod_gs is selected as the name. Click Edit > Analysis/Study … • Ensure that the rod_static study is selected. Press CTRL and selected rod_thickness, piston_neck and round from the Variable field. Click Delete Row to delete the three design variables. Crank_neck should be the only variable left. • Verify Steps is set to 4. Click Options and select the Repeat P-Loop Concergence check box. Click Close and OK to close the Sensitivity Study definition dialog box. NOTE - Conceptually, it’s not difficult to determine that by increasing the rod thickness, you decrease stress and increase mass. Hence, you run a global sensitivity study on the crank neck feature to determine how stress and mass are affected by changing its value. • Click Configure Run Settings

.

Click Create Elements during run. Choose the

icon to

run this analysis choosing yes for error detection. Press to watch the report of the analysis as it runs. After a few minutes the report should state Run Completed. Task 2 – Review global sensitivity results. • Choose Analysis > Results to start defining Mechanica results. Do not save the model if icon to create a result window definition. prompted. Choose Insert > Result window or the • Enter Crank_Neck_Mass as the name of the window and enter Crank Neck Mass as the title. Ensure that rod_gs and rod_static are listed as the Design Study selections. Ensure that the Display type is set to Graph and the Quantity is set to display Measure. Click Define Measure , select total mass, and click OK. Click OK and Show to finish the definition and display the result window. to copy the existing result windows. Enter Crank_Neck_VM as the name of the • Click Copy window and enter Crank Neck Von Mises as the title. Click Define Measure , select max_stress_vm, and click OK. Click OK and Show to finish the definition and display the result window.

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Figure 8 – Graphical Results from the Global Sensitivity Analysis Review the plots and determine the following information : o Which effect has the crank neck on the mass? o Which effect has the crank neck on the stresses? The observations above will help us to prepare the optimization, where our goal is to find the values for all the parameters to decrease the stress and mass in rod.prt. • Click File > Exit Results > No to close the Mechanica results window.

VIII. Optimization Design Study An optimization study adjusts one or more parameters to best achieve a specified goal or to test feasibility of a design, while respecting specified limits. To create an optimization study, you define the following compoments : o Goal – You select a measure to minimize or maximize as the study’ goal. o Limits – You define limits on one or more measures that Mechanica cannot violate during the optimization. o Parameters – You select one or more design parameters you want Mechanica to adjust to achieve the goal. You will also define a range and initial value for each parameter. Mechanica adjusts the model's parameters in a series of iterations through which it tries to move closer to the goal while satisfying any limits. If you have no goal, Mechanica simply tries to satisfy your limits. An optimization with no goal is sometimes called a feasibility study. If you do not define a goal, you must define limits. Without a goal, Mechanica searches for the first feasible design that satisfies the limits you define.

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Module CE4 GM4-MIQ4-PL4 When defining a goal and limits, you can select measures associated with different analysis types. You can set up an optimization that would perform any of Mechanica's analysis types except contact. For example, you could optimize the rod for stress, displacement, natural frequencies (modes), and temperature simultaneously. We run an optimization study to find a set of dimensions that optimize the connecting rod. The goal is to reduce the total mass in this model while limiting the maximum Von Mises stress to under 14 MPa. Task 1 – Define the optimization design study. • Choose Analysis > Mechanica Analyses/Studies File > New Optimization Design Study.

. Create a new static analysis by clicking

• Enter rod_opt as the name. Ensure the Goal is to minimize the total mass. Click max_stress_vm then OK. Set max_stress_vm < 14 MPa. • Pick the • Pick the • Pick the

and choose

icon and select Extrude 2 in the model tree. Select the 1 dimension. icon and select Sketch 1 in the model tree, and select the 8 dimension. icon and select Sketch 1 in the model tree, and select the 4 dimension.

• Select the design parameters rod_thickness, piston_neck, crank_neck and set their values according to the following table: Design Parameter crank_neck

Minimum Value 3

Initial Value 4

Maximum Value 8

piston_neck

3

8

8

rod_thickness

1

1

2

Table 2: Optimization Study Values • Click Options and set the Optimization Convergence value to 2% and the Maximum Iterations to 10. Select Repeat P-Loop Convergence. Click Close and OK. NOTE - The analysis will take a considerable amount of time to complete. Do not run the analysis you created. The results from the rod_opt analysis are available for review. Task 2 – Analyse the results. • Open the report files located in ~\TP6\Part2\Results\rod_opt\rod_opt.rpt with blocnote and examine the run. • Click File > Exit Results > No to close the Mechanica results window. Close the file rod.prt. Task 3 – Update the current part design dimensions to those of the optimized design. • Define the ~\TP6\Part2\Results folder as the Set Working Directory. Open the file rod.prt in this directory. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 and select the study • Select Applications > Mechanica > Mechanica Analyses/Studies rod_opt. In Info tab, select Optimize History. Press Enter when prompted to review the next step. Repeat to advance to the next step. NOTE - The design parameters update so that the model progresses to its optimized state. The model should look as shown figure 9.

Figure 9 – Optimized Shape. Task 3 – Create results windows. • Click Result windows to create a result window definition. Enter VM_rod_opt_pass as the name of the window and enter Von Mises Stress Pass as the title. Ensure that rod_opt and rod_static are listed as the Design Study selections. Ensure that the Display type is set to Graph and the Quantity is set to display Measure. Click Define Measure , select max_stress_vm, and click OK. Click OK and Show to finish the definition and display the result window. • Click Copy to copy the existing result windows. Enter Mass_rod_opt_pass as the name of the window and enter Mass Pass as the title. Click Define Measure , select total_mass and click OK. Click OK and Show to finish the definition and display the result window. • Click Copy to copy the existing result windows. Enter Max_displ_rod_opt as the name of the window and enter Maximum Displacement Pass as the title. Click Define Measure , select max_disp_mag and click OK. Click OK and Show to finish the definition and display the result window.

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Figure 10 – Rod Optimization Graphical Results. The results show the measure variation during the optimization. Notice the maximum Von Mises stress changes. ¾ Does the optimized model satisfy all constraints? ¾ Is the optimal shape reach? • Now, create result windows for Von Mises and displacement stress fringe (see Figure 11). ¾ Where is located the high stress? ¾ Is the maximum displacement acceptable?

Figure 11 – Rod Optimization Fringe Plot Results. PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 IX. Review So what should you have learnt? ¾ How to describe the purpose of design parameters. ¾ How to create design parameters and measures. ¾ How to setup and run a local and global sensitivity studies. ¾ How to review sensitivity plot. ¾ How to setup and run optimization studies. ¾ How to view the optimized model. Any problems with these? Then you should go back through the tutorial – perhaps several times – until you can complete it without any help.

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PART 3 Thermal Finite Element Analysis I. Introduction It is anticipated that before starting this tutorial that you have completed the tutorial ‘Introduction to Finite Element Analysis’. You should therefore be familiar with the process of defining constraints, loads, materials and running analyses. If you are familiar with these techniques then the transition to performing thermal analyses will be straight forward as there is a direct correlation between stress and thermal analysis. In a stress analysis loads (N) are applied to the model – in thermal analysis the equivalent is a thermal load measured in Watts. In a stress analysis boundary conditions are applied (known as constraints) which restrict the movement of the model – in thermal analysis the equivalent boundary constraints are either temperature (ºC) or convection coefficient (W/m2K). A sample model of a saucepan is provided for you to work with in this tutorial. This part should be downloaded to your working directory ~\TP6\Part3 before starting the tutorial.

II. Starting a Thermal Analysis You are now ready to start the analysis process. We will be investigating a relatively simple problem. If the saucepan is stood on the hot cooker for a long period of time how hot will the handle get – will it be too hot to hold? We are not interested in the heating up period just the steady state conditions after which the saucepan will not get any hotter. • Choose Applications > Mechanica now to take your model into analysis. Click OK on the box notifying you of the units of your model. The Model Type dialog should appear. This tutorial covers the structural analysis only. Make sure the Mode option is set to Thermal and click OK.

III. Defining Thermal Loads The first step is to define the thermal loads on this saucepan. Thermal loads are heat sources applied to the model. In this case the heat source is the gas flame or an electric element which applies heat to the base of the pan. • First, we need to define the exact area where the heat source will be apply. This is done in Mechanica using Insert > Surface Region > Sketch > OK. Pick the base of the pan as the sketch plane then OK > DEFAULT to enter sketcher. Draw a circle as shown in Figure1a. After exiting sketcher choose the base of the pan to include then OK. • Choose Insert > Heat Load then pick Surface from the side menu or choose the icon. Select the base of the saucepan as the heat source and fill in the name as HeatSource and enter a heat load value Q of 2500 W as shown in Figure 1.

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a)

b)

Figure°1 – Thermal Load.

c)

IV. Defining Boundary Conditions For this analysis the boundary conditions occur where the heat dissipates from the saucepan into the ambient air by means of convection. • Choose Insert > Convection Condition then pick Surface from the side menu or choose the icon. Select all the surfaces of the saucepan except the base (hold CTRL key whilst picking) and fill in the name as Ambient and enter a convection coefficient of 0.03 and a Bulk Temperature (the temperature of the ambient air) as shown in Figure 2.

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Figure°2 – Ambient Air Boundary Conditions.

V. Defining Materials The final definition for this analysis is to determine the material for the saucepan. • Choose Properties > Materials and the Materials dialog will appear. Scroll down the Materials in Library to find AL2014 and double click on it to transfer it to this model. If you choose Edit you will see the material parameters defined for aluminium – the most important ones are Specific Heat Capacity and Thermal Conductivity. Choose Properties > Materials assignment dialog.

and click on the saucepan and OK to assign the material. Close the material

VI. Running an Analysis That’s it you are ready to run an analysis. • Choose Analysis > Mechanica Analyses/Studies and the dialog in Figure 3 appears. From this dialog choose File > New Steady State Thermal and type the name Saucepan and press OK. Notice the method is single pass adaptive. This method is used for quick checks to ensure everything is defined correctly and to get rough results quickly. For more accurate results you would change this to multi pass adaptive. Leave it as it is for now and OK. Choose the icon

to

run this analysis choosing yes for error detection. Press to watch the report of the analysis as it runs. After a few seconds (longer on a slower machine!) the report should state Run Completed. Close the Report dialog and the Analyses dialog.

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Figure°3 – Analyses and Design Studies Dialog

VII. Seeing the Results • Choose Analysis > Results to start defining Mechanica results (Note : this icon was available in the Analyses dialog as well). The main graphics window will go blank and the menus and icons will all change. Choose Insert > Result window or the icon to create a result window and click (not double definition. In the Result Window Definition dialog that appears press click) on the folder which is the same name as the analysis that is Saucepan.

Figure°4 – Results Definition. The resultant plot shows the temperature distribution over the saucepan where the colours show the temperature ranges and the values are shown on the scale to the right. • Choose Info > Dynamic Query to get more feedback on actual values. Now as you move the cursor over the model you will get the actual value at the cursor reported in the dialog box. You will see that the end of the handle is at around 40-50ºC. Is this too hot to hold?

VIII. Additional Analysis PLATE-FORME MECANIQUE

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Module CE4 GM4-MIQ4-PL4 You have now learnt the basics of thermal analysis. By returning to the modelling window and changing certain parameters you could answer various questions related to this design. Try to answer the following questions now: o What is the effect on the handle temperature if the material is changed to STEEL? o To accommodate the change to steel the main part of the saucepan must be increased in thickness to 4mm thick. What is the effect on the handle temperature? o How high can the heat load be increased before an aluminum saucepan would melt at 600ºC? o The inside surface of the aluminum saucepan is coated in a nonstick material which reduces the convection coefficient to 0.02. What is the effect on the handle temperature?

IX. Combining Analyses One of the consequences of heating things up is that they expand. This expansion is directly related to the temperature rise and can be calculated using the coefficient of expansion for that material. Mechanica knows about this to so it can calculate the expansion for you. This is done using a structure analysis. Here is how – but you should have covered structural analyses in the previous tutorial so the instructions will be brief. • From the Mechanica modeling window change to structural analysis by choosing Edit > Mechanica Model Type. Like all structural analyses the model must be constrained. Lets assume the cook has picked up this saucepan (using an oven glove if necessary!) so to (roughly) simulate this Insert > Displacement constraint to the Surface at the very end of the handle. Fix movement in all directions.

Figure°5 – Displacement Constraint. • The second thing required for a structural analysis is a load. In this case the load is due to the expansion caused by the temperatures already calculated in the Saucepan thermal analysis. These can be applied using Insert > Temperature Load > MEC/T…The Design Study and Analysis should already be set to Saucepan in the MECT Temperature dialog. This means that the temperatures previously calculated will be applied over the whole model causing differential amounts of expansion. The final thing required for a structural analysis is a material but you have already assigned that as part of the thermal analysis so there is no need to do that here. PLATE-FORME MECANIQUE

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• Choose Analysis > Mechanica Analyses/Studies

. From this dialog choose File > New

Static and type the name Expansion and OK. Choose the icon to run this analysis choosing yes for error detection. If you get an error message about model having changed since thermal analysis was run simply choose Edit > Mechanica Model Type to change to thermal mode – run to watch the report the analysis again – return to structure mode and run this analysis). Press of the analysis as it runs. After a few seconds the report should state Run Completed. Close the Report dialog and the Analyses dialog. • To see the results choose Analysis > Results

. Choose Insert > Result Window or the

and click (not double click) on icon. In the Result Window Definition dialog that appears press the folder which is the same name as the analysis that is Expansion. Make sure all the options are the same as in Figure 6 and also that Deformed is ticked in the Display Options tab then click OK and Show.

Figure°6 – Expansion Results Definition. In this plot the colours denote the internal stresses due to expansion and the shape is the exaggerated shape due to expansion. (Note temperature loads can be combined with any other structural load so you could for example add a gravity load to the saucepan and see the stresses due to gravity as well though they would be small compared to thermal expansion.)

X. Review So what should you have learnt? ¾ How to start analysis. ¾ How to define thermal loads, boundary conditions and materials. ¾ How to run a thermal analysis. ¾ How to show results of a thermal analysis. ¾ How to use temperature loads in structural analyses. Any problems with these? Then you should go back through the tutorial – perhaps several times – until you can complete it without any help.

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PART 4 From Mechanism Studies to Mechanica I Introduction Now let’s have a look on the Cable_grip assembly we studied early. We want now choose a load set for transfering into the ProEngineer Structural Analysis package. You can download the Cable_grip.asm assembly to your working directory ~\TP6\Part4.

II. Setup the Load Transfer to Structure • Choose Applications > Mechanism now to take your model into analysis. • To see the assembly in operation it is necessary to edit the Open_Release analysis. When this is done you should be able to press the Run button at which point the spring will expand and the mechanism will be moved through its full range of movement – you should see the movement on the screen. • You can now transfer the resultant loads into Mechanica by choosing File > Use in Structure. Select the Lever.prt for the body and select the Lever.prt for the component. NOTE – o Body: In mechanism multiple components can be merged into one rigid "body" for motion purposes. By selecting a body, you are telling ProEngineer which moving group of component you wish to pull the loads from. o Component: The component defines which local coordinate system the loads will be in relation to. Choose the part or assembly you are going to analyze in structure for the component. • Choose Single Max Load from the Evaluate At pulldown. Select the Cam Follower1 joint from the pulldown. Deselect the zero or near-zero loads from the dialog. • Click OK.

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Figure°1 – Load Export Dialo. NOTE – By selecting Single Max Load, you are asking ProEngineer to choose the loads at a single point in time based on the maximum of one selected load. If you would choose Max for All Loads, them ProEngineer would take the maximum of all the loads regardless of the time at which they occured. This can lead to a very imbalanced set of loads and accelerations.

III. Setup lever.prt for Structural Analysis Task 1 – Open lever.prt and Access Structural Analysis. • File > Open Lever.prt. If Warning dialog pops up. • Choose Applications > Mechanica. Click on Continue in the Unit Info Message Box. Task 2 – Assign the Material Properties. • Click

to check or set the material properties assigned to the part.

You can see that the material called Steel is in the model. When highlighted in the list, any parts that have that material set are also highlighted in red wireframe. Notice the unit drop-down lists. This functionality allows you to enter material properties in with any common units and the system will convert them to the current working units behind the scenes. You can also select a unit from the list and it will convert the value listed. • Click OK.

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Figure 2 – Material Definition. Task 3 – Apply Loads. • Choose Insert > Mechanism Load from the toolbar. Select all the loads transferred from the mechanism dynamic analysis and click OK.

Figure 3 – Mechanism Load Import. Notice the load vectors (there are 5 of them). They point towards a point in space where the load was resolved from Mechanisms. You need to distribute these point forces and moments onto surfaces in the model. • Double-Click on the following highlighted load vector (or label):

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Figure 4 – Load Force 1. • This brings up that force's detail page. Notice that the References selection is ready to select Surface(s). Select the inside of the hole in the Lever.prt. Select OK from the Select dialog (or just click . Click Preview. Notice that the force, which is not centered on the hole, is resolved to a distributed moment and shear force on the hole. • Click OK. Double-click the adjacent moment arrow (or label) and repeat the same process to the same hole as before.

Figure 5 – Load Moment 1. • Moving to the cable end of the lever part and double-click on each of the two force/moments and use the same method to distribute those loads to the pivot hole (shown highlighted below).

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Figure 6 – Load Force and Moment 2. • Double-click the last force and apply it to the cylindrical surface that holds the cable in place.

Figure 7 – Load Force 3. • When finishished with all 5 loads, your model should look something like this.

Figure 8 – Total Load Force and Moment. Task 4 – Hide Load. • To clean up the display a bit and make the constraints more visible, click View > Simulation Display ( ) to open the Simulation Display dialog. On the Set Visibilities tab, unselect MechanismLoadSet1.

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Figure 10 – Simulation Display Dialog.

IV. Run the Structural Analysis Task 1 – Define the Analysis. • Click on to open the analysis definition dialog. Choose File > New Static. Enter the name for the new analysis: Lever_Static. • Enter the description: “Static Analysis of the Lever part using Mechanism derived loads”. • Choose MechanismLoadSet1 and the Inertia Relief option. • Choose Single-Pass Adaptive for the solution method. Task 2 – Run the Sepup Option. • Click . This opens the Run Settings dialog: o Both directories (Output Files and Temporary Files) should be set to your current working directory. If not, change them here. o Select Use Element from Existing Mesh File (to reuse the earlier saved mesh). If not available, select Create Elements during Run. o Leave Output File Format set to Binary. o Set the Memory Allocation to approximately 1/2 of your available RAM. A setting of 256 MB (or even less) is fine for this problem. • Click

to start the analysis run. Task 3 – View the Analysis Results.

• Analyse the stress and displacement of the lever part.

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Figure 11 – Analysis Results.

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