3-D Buckling Analysis Using RADIOSS - RD-1040: Exercise

3-D Buckling Analysis using RADIOSS - RD-1040
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All of the files referenced in the RADIOSS tutorials are located in the HyperWorks installation directory under
<install_directory>/tutorials/hwsolvers/radioss/.
Overview
In this tutorial you will learn the steps required to perform a buckling analysis using RADIOSS. The figure below illustrates
the structural model used for this tutorial.
Structural model with static loads and constraints applied.
This tutorial will use the following steps to set up the structural model for a buckling analysis:
Create boundary conditions for buckling analysis
Post-process results
Exercise
Step 1: Launch HyperMesh, set the RADIOSS, OptiStruct User Profile and retrieve the file
buckling.hm
1. Launch HyperMesh.
2. Choose RADIOSS in the User Profile dialog.
3. From the extended list, select Bulk Data.
This loads the User Profile. It includes the appropriate template, macro menu, and import reader, paring down the
functionality of HyperMesh to what is relevant for generating models in Bulk Data Format for RADIOSS and OptiStruct.
file://C:\Altair\hw9.0\help\hwsolvers\rd1040.htm
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The User Profiles Graphic User Interface (GUI) can also be accessed from the Preferences pull-down menu on the
toolbar.
4. From the File pull-down menu on the toolbar, select Open.
An Open file browser window pops up.
5. Find the buckling.hm file, located in the HyperWorks installation directory under
<install_directory>/tutorials/hwsolvers/radioss/.
6. Click Open.
The structural model has already been set up to contain the necessary elements, parts, property, and material data.
Step 2: Create load collectors

Create three load collectors (SPC, Static load and Buckling load) and assign each a color. Follow these steps for each load
collector.
1. Right-click inside the Model Browser window and activate the menu over Create and click LoadCollector.
2. In the Name: field, enter SPC.
3. Leave Select type: field to None.
4. Click color and select a color from the color palette.
5. Leave Select type: field to None.
6. Click Create.
7. Similarly create a LoadCollector called Static load.
8. Create a LoadCollector with the Name: Buckling load.
9. Set the Select type: to EIGRL.
10. Select a different color from the color palette.
11. Click Create/Edit.
12. Click ND to edit the field, enter in a value of 2 in the text box, and press enter.
This tells RADIOSS you would like to extract the first two buckling modes.
13. Click return to leave the panel.
Step 3: Create loads and boundary conditions for the model

For the nodes in the following figure that show constraints, we need to create these constraints and assign them to the
load collector, as outlined in the following steps.
1. From Model Browser expand LoadCollector, right-click on SPC, and click Make Current.
2. From the Analysis page, enter the constraints panel.
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3. Select all of the nodes on the bottom face of the beam, as shown in the following figure. (nodes: on Plane).
Nodes to be selected for constraint boundary conditions.
4. Deselect the degrees of freedom dof4 through dof6.

5. Click the green create button to create the necessary boundary constraints.
6. Click return.
7. From the Model Browser, expand LoadCollector, right-click on Static_Load, and click Make Current.
8. From the Analysis page, enter the forces panel.
9. Select all of the nodes on the top face of the beam, as indicated in the figure below.
Nodes selected for application of static forces.
10. Set magnitude= to -10000.

11. Click the selector beside N1N2N3 and select z-axis.
12. Click create the forces should appear.
13. Click return.
Step 4: Create a RADIOSS loadstep (also sometimes called subcase)

The last step in establishing boundary conditions is the creation of a subcase.
1. From the Analysis page, enter the loadsteps panel.
2. Click name=, enter Linear, and click Enter.
3. Set the type: as linear static.
4. Check the box preceding SPC.
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An entry field appears to the right of SPC.

5. Click on the entry field and select SPC from the list of load collectors.
6. Check the box preceding Load and select Static_Load from the list of load collectors.
7. Click Create.
A RADIOSS subcase has been created which references the SPC in the load collector SPC and the forces in the load
collector Static_Load.
8. Click name=, enter Buckling, and click Enter.
9. Select type as linear buckling.
10. Check the box preceding SPC.
An entry field appears to the right of SPC.
11. Click on the entry field and select SPC from the list of load collectors.
12. Check the box preceding METHOD(STRUCT) and select Buckling_Load from the list of load collectors.
13. Check the box preceding STATSUB and select Linear from the list of load collectors.
A STATSUB card allows for the selection of a linear static subcase for buckling analysis.
14. Click Create.
15. Click return to go back to the Analysis page.
Step 5: Run both the linear and buckling analysis

1. From the Analysis page, enter the RADIOSS panel.
2. Click save as following the input file: field.
A Save file browser window pops up.
3. Select the directory where you would like to write the RADIOSS model file and name your input file (buckling.fem
example) and click Save.
4. Set the export options: toggle to all.
5. Click the run options: switch and select analysis.
6. Set the memory options: toggle to memory default.
7. Click Radioss to launch your job.
This launches the RADIOSS job. If the job is successful, you should see new results files in the directory where
HyperMesh was invoked. The buckling.out file is a good place to look for error messages that will help you debug
your input deck if any errors are present.
The default files that will be written to your directory are:
buckling.h3d
HyperView binary results file.
buckling.res
Results file which contains everything from displacement to stress

results that can be viewed in the Post page within HyperMesh.
buckling.out
ASCII based output file of the model check run before the simulation
begins and gives some basic information on the results of the run.
buckling.stat
Detailed breakdown on the CPU time used for each significant stage in
the analysis.
Process: Post process the results in HyperView
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RADIOSS will give you contour information for all of the loadsteps that were run. This section describes the process for
viewing those results in HyperView.
Step 6: View results of Linear Loadstep: von Mises contour stress

1. From the RADIOSS panel, click the HyperView button.
HyperView launches with the buckling.h3d file which contains the model and the results.
2. Click in the bottom of the GUI to activate the Load Case and Simulation Selection dialog.
3. Select Subcase 1 Linear, listed under Load case (shown below) and click OK.
4. From the Graphics pull-down menu, click on Contour.

5. Choose Element Stresses (2D and 3D) as the Result type and select the sub type to von Mises.
6. Click Apply.
This should show the contour of von Mises stress.
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Step 7: View results of Buckling Loadstep: Deformed shape and Animating Results
1. Click Clear Contour.
2. Click on the > at the bottom of the Load Case and Simulation Selection to activate Subcase 2 Buckling
make sure the simulation is for Mode 1.
3. Click the Deformed panel toolbar button
4. Under Deformed shape:, enter a Value of 10.

5. Under Undeformed shape:, for Show:, select Wireframe from the drop down list.
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6. Click the animation toolbar button to view the animation
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Similarly we could check the results for the 2nd mode.

Go To
RADIOSS, MotionSolve, and OptiStruct Tutorials
6/10/2009

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