# HS-4220: Size Optimization Study on an Impact Simulation Using RADIOSS

Learn how to perform a size optimization on a finite element model defined for RADIOSS.

Before you begin, copy the model files used in this tutorial from <hst.zip>/HS-4220/ to your working directory.

The RADIOSS model shown in Figure 1 is run using the RADIOSS Starter and Engine.

The objective is to minimize the mass of the beam under the following constraints:
• Internal energy must be more than 450
• Resulting reaction force must be less than 75
The input variables are the thicknesses of the four components defined in the input deck boxbeam1._0000.rad via the /PROP/SHELL entries. They are combined into two input variables. The thickness should be between 0.5 and 2.0; the initial thickness is 1.0. The optimization type is size.

## Create Base Input Template

In this step, create the base input template in HyperStudy.

1. Start HyperStudy.
2. From the menu bar, click Tools > Editor.
The Editor opens.
3. In the File field, navigate to your working directory and open the file boxbeam1_0000.rad.
4. Create parameter for /PROP/SHELL/1.
1. In the Find area, enter /PROP/SHELL/1 and click .
HyperStudy highlights /PROP/SHELL/1 in the boxbeam1_0000.rad file.
2. Highlight the field for thickness.
Tip: To assist you in selecting 20-character fields, press Ctrl to activate the Selector (set to 20 characters) and then click the value.
3. Right-click on the highlighted fields and select Create Parameter from the context menu.
The Parameter: varname_1 dialog opens.
4. In the Label field, enter Upper part.
5. Change bounds.
• Lower Bound: 0.5
• Nominal: 1.0
• Upper Bound: 2.0
6. In the Format field, enter %20.5f.
7. Click OK.
5. Assign /PROP/SHELL/2 the same thickness as /PROP/SHELL/1.
1. Find /PROP/SHELL/2 and highlight the field for thickness.
2. Right-click on the highlighted fields and select Attach to > varname_1 from the context menu.
6. Create parameter for /PROP/SHELL/3.
1. Find /PROP/SHELL/3 and highlight the field for thickness.
2. Right-click on the highlighted fields and select Create Parameter from the context menu.
The Parameter: varname_2 dialog opens.
3. In the Label field, enter Lower part.
4. Change bounds.
• Lower Bound: 0.5
• Nominal: 1.0
• Upper Bound: 2.0
5. In the Format field, enter %20.5f.
6. Click OK.
7. Assign /PROP/SHELL/4 the same thickness as /PROP/SHELL/3.
1. Find /PROP/SHELL/4 and highlight the field for thickness.
2. Right-click on the highlighted fields and select Attach to > varname_2 from the context menu.
8. Click OK to close the Editor.
9. In the Save Template dialog, navigate to your working directory and save the file as boxbeam1.tpl.

## View Base Input Template in TextView

1. Open HyperMesh Desktop.
2. On the Client Selector toolbar, select TextView.
3. Open base input template.
1. From the menu bar, click File > Open > Document.
2. In the Open Document dialog, open the boxbeam1.tpl file.
The text editor displays the following input variables that are defined by Templex parameter statements:
{parameter(varname_1, "Upper part",    1.00000,    0.50000,    2.00000)}
{parameter(varname_2, "Lower part",    1.00000,    0.50000,    2.00000)}
4. Find /PROP/SHELL.
1. On the Text toolbar, click (Find).
2. In the Find dialog, Find field, enter /PROP/SHELL.
3. Click .
The parameterized /PROP/SHELL cards, which reference the input variables, highlights.
4. Close the dialog.
5. On the Text toolbar, click .
The text editor evaluates the Templex statements, and replaces the parameters with their initial values.
6. Repeat step 4 and search /PROP/SHELL again.
You will find the following:
7. Close HyperMesh Desktop.
Note: You do not need to save the session.

## Perform the Study Setup

1. Start a new study in the following ways:
• From the menu bar, click File > New.
• On the ribbon, click .
2. In the Add Study dialog, enter a study name, select a location for the study, and click OK.
3. Go to the Define Models step.
4. Add a Parameterized File model.
1. From the Directory, drag-and-drop the boxbeam1.tpl file into the work area.
2. In the Solver input file column, enter boxbeam1_0000.rad.
This is the name of the solver input file HyperStudy writes during the evaluation.
3. In the Solver execution script column, select RADIOSS (radioss).
5. Define a model dependency
1. Click Model Resources.
The Model Resource dialog opens.
2. Select Model 1 (m_1).
3. Click Resource Assistant > Add File.
4. In the Select File dialog, navigate to your working directory and open the boxbeam1_0001.rad file.
5. Set Operation to Copy.
6. Click Close.
6. Click Import Variables.
Two input variables are imported from the boxbeam1.tpl resource file.
7. Go to the Define Input Variables step.
8. Review the input variable's lower and upper bound ranges.

## Perform Nominal Run

1. Go to the Test Models step.
2. Click Run Definition.
An approaches/setup_1-def/ directory is created inside the study Directory. The approaches/setup_1-def/run__00001/m_1 directory contains the input file, which is the result of the nominal run.

## Create and Evaluate Output Responses

In this step you will create two output responses.

1. Go to the Define Output Responses step.
2. Create the Energy output response, which is the initial energy of the model.
1. From the Directory, drag-and-drop the boxbeam1T01 file, located in approaches/setup_1-def/run__00001/m_1, into the work area.
2. In the File Assistant dialog, set the Reading technology to Altair® HyperWorks® and click Next.
3. Select Single item in a time series, then click Next.
4. Define the following options, then click Next.
• Set Type to Global Variables.
• Set Request to Internal Energy.
• Set Component to MAG.
5. Label the output response Energy
6. Set Expression to Maximum.
7. Click Finish.
3. Create the Force output response, which is the resultant reaction force in the Z-direction.
1. From the Directory, drag-and-drop the boxbeam1T01 file, located in approaches/setup_1-def/run__00001/m_1, into the work area.
2. In the File Assistant dialog, set the Reading technology to Altair® HyperWorks® and click Next.
3. Select Single item in a time series, then click Next.
4. Define the following options, then click Next.
• Set Type to Rigid wall/Wall Force.
• Set Request to 1 RWALL 1.
• Set Component to FNZ-Z NORMAL FORCE.
5. Label the output response Force
6. Set Expression to Maximum.
7. Click Finish.
4. Create the Mass output response.
1. From the Directory, drag-and-drop the boxbeam1T01 file, located in approaches/setup_1-def/run__00001/m_1, into the work area.
2. In the File Assistant dialog, set the Reading technology to Altair® HyperWorks® and click Next.
3. Select Single item in a time series, then click Next.
4. Define the following options, then click Next.
• Set Type to Global Variables.
• Set Request to Mass.
• Set Component to MAG.
5. Label the output response Mass
6. Set Expression to First Element.
7. Click Finish.
5. Click Evaluate to extract the response values.

## Run Optimization

1. Add an Optimization.
1. In the Explorer, right-click and select Add from the context menu.
2. In the Add dialog, select Optimization.
3. For Definition from, select Setup and click OK.
2. Go to the Optimization > Definition > Define Output Responses step.
3. Click the Objectives/Constraints - Goals tab.
4. Apply an objective on the Mass output response.
1. Click Add Goal.
2. In the Apply On column, select Mass.
3. In the Type column, select Minimize.
5. Apply a constraint to the Energy output response.
1. Click Add Goal.
2. In the Apply On column, select Energy.
3. In the Type column, select Constraint.
4. deterministic
5. In column 1, select >= (less than or equal to).
6. In column 2, enter 450.
6. Apply a constraint to the Force output response.
1. Click Add Goal.
2. In the Apply On column, select Force.
3. In the Type column, select Constraint.
4. deterministic
5. In column 1, select <= (less than or equal to).
6. In column 2, enter 75.
7. Go to the Optimization > Specifications step.
8. In the work area, set the Mode to Adaptive Response Surface Method (ARSM).
Note: Only the methods that are valid for the problem formulation are enabled.
9. Click Apply.
10. Go to the Optimization > Evaluate step.
11. Click Evaluate Tasks.
12. Go to the Optimization > Post-Processing step.
13. View iteration history of optimization.
1. Click the Iteration History tab to display data in a tabluar view.
The optimal design is highlighted green, the infeasible designs are shown with red text, and the violated constraints are indicated in bold text.
2. Click the Iteration Plot tab to plot the iteration history of the study's objectives and constraints.
In the initial design, the design was infeasible as indicated by the large circular marker for the first iteration. A view of the constraint plots shows that the second constraint was violated in the initial design. Initially, the optimizer added some weight in order to satisfy the design constraints. Notice that both constraints are near their bounds in the optimal design.