PTC Creo - Analyzing 3D Structures

Tutorial 1 3D Models

3-1

CHAPTER 3: Analyzing 3D Structures

Chapter Summary: This chapter introduces the procedure for solving a 3D structure problem in Creo Parametric. Several features of the software that are necessary for running a 3D model are explored. The command and menus required for the analysis are introduced. The tutorial outlines step-by-step procedure for preparation of the analysis, running the analysis, and obtaining the results. Key Features 1. Preparation of the model for FEA 2. Preparing the analysis

Applying loads, constraints and material properties Setting the Convergence Display options for the model Discussion of the Results File Plots and interpretation of Results

Tutorial 1: Application of 3D Model and 3D elements 3.1 An Overview As detailed in Chapter 2, Creo utilizes four different types of models and six types of elements. The Creo Model Setup window discussed in Chapter 2, and repeated here in Figure 3.1, lists the model types; with the 3D option selected by default (shown with the shaded radio button under the Type header). The 3D model type is the most general type of model and can be used for, in general, any structure. However, since the elements used are 3D elements, the number of nodes and elements needed for an analysis could be very high, requiring excessive execution time. Depending on the geometry and the boundary conditions, some structural problems can be solved with simpler and less time consuming models and elements (Idealization), which we will explore in the following tutorials. This tutorial will focus on the analysis of a 3D model using 3D elements (the Creo default). We will analyze a simple shaft, shown in Figure 3.2(a). Figure 3.1: Model Setup


3-2

3.2 Problem Definition For the steel hollow shaft shown, find the maximum stresses and deflections in the shaft. The left end is fixed and 8,000 lbs. force is applied at the right end.

Figure 3.2(a): The shaft Figure 3.2(b): Shaft-Section Dimensions 3.3 CREATING THE MODEL Creo is a top-down software, where, a CAD model is created first, and then the software creates the nodes and elements by mathematically dividing the structure into finite sections, or as known in FEA, elements. So our first step is to create the model, as outlined below. Start the Creo and create a new directory. Name the directory as Tutorial 1. Save all your work for the tutorial in this directory. Set Tutorial 1 as the Working Directory and create a 3D model of the shaft. If you have exited the directory, make sure to set the Working Directory to Tutorial 1. Start a new Part file by clicking on the New File icon on the menu located at the top of the screen. Name the file as shaft3d. Using the directions given below, set the units to IPS. Note: The default units in Creo are in lbm Sec. Since these units are in terms of mass, and not force, they should not be used in structural analysis. The mass units are useful in Pro/E models, primarily for calculating mass moment of inertia. If the default units (in lbm sec) are used for stress analysis, the stress values would be much higher, by a factor of 386 in/s2 (g = F/m value). 3.3.1 TO SET YOUR UNITS, FOLLOW THESE STEPS: On top of the Creo screen, click on File > Prepare> Model Properties. This will open the Model Properties window. In the Model Properties window, the second line from top of the window gives you options for setting the units. Click on change to open the Units Manager window. Click on the option: Inch Pound Second (IPS).


3-3

Select the option Set. This will open another window, which will give you two options: 1) Convert Dimensions, and 2) Interpret Dimensions. If you havent created the model, either option can be selected. However, if the model has been created, select the second option so that the dimensional values that you assigned to your model are interpreted in the IPS units. 3.3.2 TO CREATE THE GEOMETRY: You can download this model and any other models in this manual from the following web site: www.engr.sjsu.edu/ragarwal/Creo_manual Also, the model can be easily created by revolving the section shown in Figure 3.2(b) around the central axis. The completed part should look as shown in Figure 3.2(a). Save the part. 3.4 FINITE ELEMENT ANALYSIS After the model is completed, the next step is to prepare it for finite element analysis, which requires defining the material properties, loads, constraints, followed by input for the type of analysis you wish to carry out. Since we are using the default 3D model, the model and element types are already selected by the software. However, if you are working with other than a 3D model, further steps are required for setting up the model. Let us take a brief look at the list of available Creo model types. Click on the menu Application > Simulate > Model Set up > Advanced You will see the Model Setup window, shown in Figure 3.3. As mentioned earlier, Creo selects the 3D model by default. Close the Model Setup window by clicking OK and return to the Simulation window; it should appear as shown in Figure 3.4. Figure 3.3: Model Setup window


3-4

3.4.1 CREO ENVIRONMENT AND THE SCREEN In Creo, the menus and icons are context sensitive. In the Simulation window of Figure 3.4, some additional the menus and icons are added for carrying out the analysis. To keep the tutorial simple and focused, will introduce only the key icons used in this tutorial.

Figure 3.4: Creo Simulation Window A brief description of the selected icons follows (refer to Figure 3.5): Load: To apply concentrated or distributed laod Constraints: To apply constraints to the model Material Properties: The top icon is used for selecting the material from the list of materials available in the software. The middle icon is used for assigning the selected material, and the bottom icon is used to define composites materials to an anisotropic model. Close: Clicking on this icon will close the Simulation window.


3-5

Load Constraints Material Analysis To close

Properties Simulation window

Figure 3.5: Simulation Menus and Icons 3.4.2 MODEL PREPARATION FOR FEA Let us prepare the model for FEA. We will apply the material properties first, followed by the Loads and then by Constraints. 3.4.3 APPLYING MATERIAL PROPERTIES Stiffness of a structure depends on the geometry and its mechanical properties. The geometry of the model has been already defined by the CAD model; now we need to specify the material properties. Creo provides a library of the most commonly used materials, which can be accessed by clicking on either the Materials or the Material Assignment icons. When you click on the Materials icon, it takes you directly to the materials library, whereas, clicking on the Material Assignment icons takes you first to an intermediate window, named Material Assignment, and from this window you are allowed to access the materials library by clicking on the More tab in the window. Access the Materials library: Click on the menu: Home > then on the Materials icon This will open the Material Library shown in Figure 3.6. The list in the library includes 20 pre-defined materials. You can create and add your own materials by clicking on the File menu and selecting New. Also, you can make changes to the properties of any material in the library. From the Materials list, double click on steel, placing it on the right side of the window. It should be highlighted in green. Click OK to exit the Materials window. Next, we will assign the selected material to the model. Click on the Materials Assignment icon This will open the Material Assignment window, shown in Figure 3.7. Note the Material STEEL being selected and placed next to the More tab. Your window should look as shown in the Figure 3.7.


3-6

Figure 3.6: Materials Library Click OK to assign the material Steel and close the window. The material is now assigned to the model; the material icon will be placed on the model, and added to the list in the model tree. Figure 3.8 shows the model with the material property icon. Figure 3.7: Material Assignment window Figure 3.8: FEA Model with the Material Property icon


3-7

3.4.4 VIEWING THE FEA MESH When you enter the Simulation environment, Creo automatically creates the element mesh, i.e., nodes and elements. You can view the element mesh using the AutoGem menu, as described below. Click on Refine Model > AutoGEM > AutoGEM. See Figure 3.9 This will open the AutoGem window, shown in Figure 3.10.

Figure 3.9: AutoGEM menus In the AutoGem window, click on the tab Create. Creo will create the element mesh and show the nodes and elements in the part, along with two new windows: AutoGem Diagnostic Mesh and AutoGem Summary. If the mesh is created successfully, the Diagnostic window will list only the number of elements created by AutoGem. The AutoGem Summary window will list the elements type and the number of each element, along with some additional elements data. You can use the Simulation Display menu to get a better view of the elements in the model. Follow these steps: Click on the Simulation Display icon. The icon is located at the top center of the screen. This will open the Simulation Display window, shown in Figure 3.11. Figure 3.10: AutoGem Window


3-8

Figure 3.11: Simulation Display Window Figure 3.12: FEA mesh with shrunken elements In the Simulation Display window, Click on the Mesh tab (the last tab in the row) and select the Shrink Elements box. Set the percentage shrinking between 25 and 35 and then click OK. Open the AutoGem Summary window if its not open (by clicking: AutoGem > Create). The part will show the shrunk tetrahedron elements, as shown in Figure 3.12. Close the Simulation Display and AutoGem Summary windows. Purpose of the AutoGem mesh display is to verify model validity for the analysis. If the model geometry is invalid, the software will give an error message, without creating a mesh. Next we will apply the boundary conditions: Loads and Constraints. 3.4.5 APPLYING LOADS The 8,000 lb. force is applied on the right end of the shaft in the negative y-direction. Since a concentrated force applied on a surface of the shaft will create extremely high stresses, we will apply it as an uniformly distributed force on the end-surface of the shaft. Follow these steps: If you have exited the Creo Simulation environment, click on the Application menu and select the Simulate tab. This will bring you to the Creo environment. When in the Creo environment, click on the Force/Moment Load icon located on top of the screen. This will open the Force/Moment Load window shown in Figure 3.13.


3-9

In the Force/Moment Load window, you can accept the default name for the load or write your own title for the applied force. Under the heading Member of Set, Creo assigns the name LoadSet1 for the first load set. If there is another load set used in the analysis, it will be titled LoadSet2. A new load set can be created by clicking on the New tab. Under the heading References, click on the fold-down arrow to view options for where to apply the force on the model. The options are; Surfaces, Edges/Curves, and Points. A concentrated force should only be applied on a line element (Beam), and not on a surface (2D Solid) or solid (3D Solid) elements. Here is a guideline for using the References options, which depend on the type of the element the force is being applied on. Element Type References 3D Surface 2D Edges/Curves Figure 3.13: Force/Moment Load window Line (1D) Points When applying a concentrated force on 2D or 3D elements, the applied force should be distributed uniformly on an edge/curve or surface, respectively. The default option Individual is pre-selected. Leave it unchanged. The space below the Surfaces option prompts you to select the surface where the loads are applied. The space box should be pink, and if its not, click in this space to activate it and then select the surface at the end of the shaft. The selected surface will turn green, ready to accept the applied load. Under the heading Force, leave the Components option unchanged and enter a value of -8,000 for y-component and leave all other force and moment components blank. If your units are correct, you should see the units lbf and in lbf at the bottom of the Force/Moment Load window. We will discuss the other options provided in the Force/Moment Load window in the subsequent tutorials. Close Force/Moment Load by clicking on OK. 3.4.6 APPLYING CONSTRAINTS Without constraints, the model is free to float in space and there would be no deflections in the model. Therefore, a model is required to be constraint so that it is allowed to deform, but restricted from a rigid body motion in any of the coordinate directions. Similar to loads, constraints are always applied at the nodes.


3-10

In general, a node has 6-degrees of freedom (DOF), three translations (along x, y, z) and 3 rotations (about x, y, z). Constraints are applied to represent the supports on the model, by suppressing the appropriate translations and rotations. Click on the Displacement Constraints icon This will open the Constraints window, shown in Figure 3.14. 3.4.7 THE CONSTRAINTS WINDOW Under the header Name, give the title Fixed_end (You could also accept the default name, if you wish). Similar to the Force/Moment Load window, the Member of Set name is assigned by the software as ConstraintSet1. The References header and the options: Surface, Edges/Curves, and Points are identical to the Load window. Figure 3.14: Constraints window The last two headers in this window: Translation and Rotation allow you to specify the constraints. A node can be free, constrained, or allowed a specified deflection. We will constrain the model in all degrees of freedom at the left-end surface of the shaft. Click in the Surface box to make sure its active (Showing pink), then select the left-end surface of the model, which will turn green, confirming it has been selected. The software pre-selects the fixed icons for Translation and Rotation. Since the model is fixed at the left-end surface, accept the defaults and click on OK. Observe the constraints icon placed on the left-end surface of the model. Creo uses the constraints symbol shown in Figure 3.15. The upper three boxes represent the status of translations along the x, y, z, directions and the lower ones represent rotations. A shaded box indicates that the node is fixed in that direction. Constraint symbol


3-11

Since the model is fixed, i.e., all six DOF are suppressed, the constraints icon on the shaft will show all the boxes shaded. We are now ready to run the analysis. 3.4.8 SETTING THE ANALYSIS PARAMETERS Prior to running the analysis, you need to define the type of analysis you wish to run (Static, Dynamic, Buckling, etc.) and other parameters, as described below. Follow the steps outlined here. On top of the Creo Simulation screen, click on the Analysis and Studies icon. This will open the Analysis and Design Studies window shown in Figure 3.16. Click on the File menu. The list shows the analyses options provided in Creo, which include the Static, Dynamic, Sensitivity, and Optimization analyses. Additionally, as listed in the window, Creo can be used to conduct Modal, Buckling, Fatigue, and Prestress analyses. In this tutorial we will limit our discussion to the Static analysis only and leave discussion of other topics for the subsequent tutorials. In the Analysis and Design Studies window, select New Static and close the window. This will open the Static Analysis Definition window shown in Figure 3.17. Figure 3.16: Analyses and Design Studies Window Explanation of the window headers follows: Name: By default, Creo assigns the name Analyis1. If you have already run an analyses earlier and saved them in the Working Directory, you should name the current analysis with a distinct name, otherwise Creo will overwrite the previously run analysis that has the default name Analysis1. Description: Write a brief description of the analysis (for your convenience only, it doesnt affect the analysis).


3-12

Constraints and Loads: The box under the heading Constraints will list all your constraints sets. If you have more than one constraint sets, you can check the box Combine Constraints Sets to apply all the listed constraints to your model, or leave it uncheck and highlight only the constraints set you would like to apply to the part. Initially, the software will highlight the Constraints and the Loads sets; however, you should always verify that the correct sets are highlighted. Convergence: Purpose of the Convergence setting is to optimize the execution time for an analysis so that the analysis will terminate when the variation in stresses or strain energy is at an acceptable level. In Creo, an analysis is executed several times by changing the edge order of the elements (p-order) while checking the variation in the Measures (VMS, Strain Energy, Deflections, etc.). When the variation in the Measure reaches less than the convergence limit, the analysis will terminate. There are three Convergence options: 1. Quick Check With this option, the model is analyzed using the elements originally created by Creo, without varying the edge shapes of any element. Figure 3.17; Static Analysis Definition As the name implies, its a quick analysis; the purpose of the analysis is to check if the analysis is valid and only the first order elements are utilized. If the analysis is valid, the results obtained in the analysis are only approximate values and should be investigated further with higher edge-order elements. Since all the element edges are of only the first order and only a single run is executed, the execution time is much shorter. Use this option for the complex models that will require a long execution time and would waste time if the analysis or the model is invalid. 2. Single Pass Adaptive (SPA) In this option, the software executes the analysis twice, the first time with a p-order of 3, and the second time by adjusting the p-order of those elements that it determines will provide more accurate results. For a model that has a large number of elements and will require a very lengthy CPU run time, Single Pass Adaptive convergence can save significant run time if the results obtained by SPA and the Multi Pass Adaptive do not differ significantly. For example, if the results obtained in a static analysis are similar in both the convergence methods, SPA would result in a significant saving of CPU run time. 3. Multi- Pass Adaptive In this option, you can set the limits for how accurate you would like to have the results. Since there is a trade off with accuracy and execution time, with increase in accuracy requirement, the execution time also increases. When you select the Multi- Pass Adaptive option, you need to select the Percentage Convergence and the Polynomial Order (p). The maximum p-order in Creo is 9. Multi Pass Adaptive


3-13

conducts series of analyses. Each run compares its results with the previous run until the desired convergence is reached.

We will run the analysis with both the options, first with the Quick Check and then the Multi-Pass Adaptive. QUICK CHECK ANALYSIS Under the header Method, select the Quick Check option. Accept all other options as they appear. Close the window by clicking on OK. This will take you back to the Analyses and Design Studies window, shown again in Figure 3.18. We have already explored the File menu in this window. The other three menus are Edit, Run, and Info and Results

The Edit menu is used to edit, delete, or copy the highlighted (shaft3d) file.

The Run menu is used to run, stop or make changes to the default Creo settings (to be discussed later)

The Info menu is to verify the validity of the model, to check the status of the analysis while its running, and to view the Optimization History after you have run the Optimization analysis.

Figure 3.18: Analyses and Design Studies window

The Results window, as the name implies, launches the Results window The icons shown below the menus can also be used to carry out the functions. You can also open the results window from the Creo screen; however, the data from the analysis will not be automatically transferred you will have to import them from the saved file. Run the analysis by clicking on the menu Run > Start or by clicking on the green flag. Select the applicable response in the Question window that opens and start the analysis. To view the progress and the results of the running analysis, Click Info > Status or click on the Run Status icon Study the Run Status window that opens. Creo creates a directory for the results file and gives it a name as shaft3d.rpt. You can open this file in the Notepad or any word processor for editing and printing your report.


3-14

Let us look at the results. The rpt file should show the max_disp_mag approximately 0.0473 in. and the max_stress_vm approximately 2.143e+04 (21,143 psi). If your values are too far off, check the geometry and the load data. You can ignore any small variation in the values. MULTI-PASS ADAPTIVE ANALYSIS We will use and edit the existing analysis file and run the Multi_Pass Adaptive analysis. Close the rpt file and click on the Edit > Analysis/Study menu in the Analysis and Design Studies window. This will open the Static Analysis Definition window. Under the header Method, click on the fold down arrow and select Multi-Pass Adaptive for the Method. Change the Polynomial Order to 9 and Percent Convergence to 2. Your completed window should look similar to Figure 3.19. Close the Static Analysis Definition window by clicking OK. This will take you back to the Analysis and Design Studies window. Following the procedure used in the Quick Check analysis, run the analysis again. Before running the new analysis, Creo will prompt you to delete the files generated by the Quick Check analysis. Click Yes to delete the old files and overwrite the files generated by the Multi-Pass Adaptive analysis. Select No for the interactive diagnostics. Creo will start the analysis. You can view the progress of the analysis by clicking on the Info > Status menu at the top of the Analysis and Design Studies window or by clicking on the Status icon. The Results File The analysis will stop after the 7th pass, which means that the specified convergence was satisfied during this pass. Depending on the computer you are using, the Total CPU Time should be less than a minute. As mentioned earlier, Creo assigns the suffix rpt to your result file name. The name shaft3d.rpt will show on the top of the file. Other useful information in the rpt file includes the followings:

System of units used Type and number of elements Data generated by each p-pass: Convergence,

number of equations (size of the stiffness matrix), and CPU Time

Applied loads Mass and mass-moment of inertia of the model

Figure 3.19: Completed Static Analysis Definition


3-15

When the analysis is successfully completed, the software prints the words: Run Completed. You can copy the file into a word processer or the Notepad and edit it. The file can be located in the Working directory, with the suffix .rpt. Figure 3.18 shows the edited rpt file. 3.4.9 RESULTS AND CONCLUSIONS The edited and partial rpt file, shown in Figure 3.20, lists the following values (your results may differ slightly):

The maximum deflection on the model = 0.048 in. Maximum Von-Mises Stress = 25,288 psi.

Measures: Name Value Convergence -------------- ------------- ----------- max_beam_bending: 0.000000e+00 0.0% max_beam_tensile: 0.000000e+00 0.0% max_beam_torsion: 0.000000e+00 0.0% max_beam_total: 0.000000e+00 0.0% max_disp_mag: 4.801840e-02 0.0% max_disp_x: -6.879836e-03 0.0% max_disp_y: -4.753570e-02 0.0% max_disp_z: -1.454624e-04 0.0% max_prin_mag: -2.753383e+04 0.1% max_rot_mag: 0.000000e+00 0.0% max_rot_x: 0.000000e+00 0.0% max_rot_y: 0.000000e+00 0.0% max_rot_z: 0.000000e+00 0.0% max_stress_prin: 2.594546e+04 0.6% max_stress_vm: 2.528855e+04 0.8% max_stress_xx: -2.615616e+04 0.2% Figure 3.20: .rpt file max_stress_xy: -9.769088e+03 0.6% max_stress_xz: 4.886693e+03 0.2% max_stress_yy: 7.638299e+03 0.7% max_stress_yz: 1.955522e+03 3.1% max_stress_zz: -5.842814e+03 2.3% min_stress_prin: -2.753383e+04 0.1% strain_energy: 1.898453e+02 0.0% Analysis "shaft3d_static" Completed (13:30:35) ------------------------------------------------------------ Run Completed Mon Jan 02, 2012 13:30:35 ------------------------------------------------------------ You can view your results in various graphical formats. Creo can plot the results data including stresses, convergence, mass, strain energy, deflections, etc. The results are plotted in the Results window. We will explore some important graphs. In the Analyses and Design Studies window (Figure 3.18), you can view the results in various graphical formats. By clicking on any of the icons shown below you can launch the Results window. Creo transfers the data file into the Results window. Experiment with each of these icons.


3-16

We will create 4 graphical results windows: Model animation, Stress contours, and a couple of Convergence plots. ANIMATION PLOT You can verify if the loads and constraints are properly applied by animating the deflection of the model. There should be no deflection at the constrained nodes and the deflection should be in compliance with the applied loads. To animate the model, Click on the first of the three icons shown above. This will launch the Results Window Definition, shown in Figure 3.21. Complete the window entries as follows: Name: shaft3d Title: Animation Design Study: shaft3d_stat Display Option: check the boxes for Deform and Animate

Figure 3.21: Results Definition Window Click OK and Show. The stresses will be plotted and shown as color coded fringes, the highest stress region shown in red and the lowest stress regions in black. A color chart gives the legend of colors and the associated stress values. See Figure 3.21. The model will animate to show the direction of its deflection. To explore the other tools of visual effects in Creo, you can experiment with the menus and icons on the top of the screen in this window Figure 3.22: Animation Plot


3-17

STRESS CONTOURS Stress contour plot provide visual maps of the stress distribution. Color of the fringes represents the magnitude of stresses. You can also use the mouse cursor to find the exact stress magnitude at any point in the model. To create the stress plot, we will make a copy of the definitions associated with the animation plot. You could also edit the window or start a new window for a new plot. However, its much easier to just copy the window definition and make the appropriate changes. In the Results window, click the Copy icon on top of the screen. This will bring back the Results Definition window. Make the following changes: Name: fringe_plot Title: Von Mises Stresses Display Type: Stress Uncheck the Deformed and Animate boxes. Click OK and Show. Creo will create another window next to the Animation window. You can activate either window by clicking inside the desired window. The active window will show with a green border, whereas, the inactive window will shown with a red border. You can view just one plot at a time or both the plots. The plots are stored and can be accessed by clicking the Display Results Window icon We will view the fringe plot in a single window. Click on the Display Results window icon. If you had both the Results windows open, the Display Results window will show and highlight the title of both the windows. You can choose to show just the fringe_plot window by highlighting the title of this window only. See Figure 3.23. Highlight only the fringe_plot title and click OK. Figure 3.23: Display Results Window Creo will show the model with color fringes, similar to the Animation plot. However, in this plot, you can explore the model further by using the Info menu. Before proceeding further, explore the options given in this menu. To locate the point of maximum Von-Mises stress, click Info > View Max. This will place a small triangle at the point of the maximum Von-Mises stress on the model, along with the value. CONVERGENCE PLOTS Now we will look at a couple of additional plots that will provide us with a better understanding of how the VMS and Strain Energy vary with variation in the element shapes (p-order).


3-18

In the Result window, click the menu Edit > Copy This will open the Result Window Definition and copy all the analysis data from the existing plot. However, if you do not wish to overwrite and save the existing window, you can edit the earlier input for the plot by clicking on the menu Edit > Results Window. Since we would like to save the previous windows, we will opt for the Copy and not the Edit option. Click File > Edit .This will open the Results Window Definition, Figure 3.24. In the Result Window Definition, delete fringe_plot and enter vm_converge for the name and VMS Convergence under the header Title. For display type, select Graph by clicking on the fold-down arrow. For Graph Ordinate, select Measure and then click on the icon. This will open the Measures window, Figure 3.25. Browse through the list in the Measures window; scroll down to view all the listed Measures, then select Max_stress_vm . Close the window by clicking OK. Click OK and Show in the Results Window Definition. Creo will open a new Results window showing the VMS Convergence plot. See Figure 3.26.

Figure 3.24: Results Window Definition Figure 3.25: Measures Window The convergence plot shows the variation of VMS with the p-order of elements. When all the elements edges are modeled with straight edges (p = 1), the VMS value is approximately 4,000 psi. As the p-order


3-19

is increased, the stress value rises, and begins to converge after the 5th order, at approximately 24,000 psi. Even though the curve is not completely horizontal, the analysis has satisfied the convergence limit (2%) that we set in the analysis. Strain Energy Convergence vs. p-pass For structures that have very high stress concentration regions, the VMS may not converge at any p-order. Since the maximum VMS represents the stress value at a single point in the structure, and only in one element, it predicts the stress variation in that element only. If the element is located in a non-critical region, the VMS convergence criterion alone is not sufficient to give us confidence in the analysis. In this case, we should use the Strain Energy Convergence; Strain Energy Convergence takes into account all the elements in the structure and is a better indicator of the convergence. To plot Strain Energy Convergence vs. p-order, we will follow the same procedure used in the VMS versus p-order plot. Figure 3.26: Convergence Plot VMS vs. p-order In the Result window (Figure 3.26), Click on the menu Edit > Copy This will open the Result Window Definition and copy all the analysis data from the existing plot. In the Result Window Definition, Figure 3.27, enter Strain_converge for the name and Strain Energy Convergence under the header Title. For display type, select Graph by clicking on the fold-down arrow.


3-20

For Graph Ordinate, select Measure and then click on the icon. This will open the Measures window. Scroll down and select the Strain Energy from the list. Your completed window should look as shown. Click OK and Show. As shown in Figure 3.28, the graph shows variation of the Strain Energy as the p-order changes.

Figure 3.27: Definition for Strain Energy Convergence

Comparison of the graphs in Figures 3.26 and 3.28 shows that the Strain Energy convergence is achieved much sooner, at the third p-order, and it is much smoother than the VMS curve. Figure 3.28: Strain Energy Convergence

CHAPTER 3: Analyzing 3D Structures

PTC Creo - Analyzing 3D Structures

Documents

d elements

model creo

d model type

d models

model types

model setup tutorial

model discussion

cad model