MSC SimDesigner Thermal (SDT) - Integrated Solutions for CATIA V5
by Antoine Reymond, MSC.Software Corporation

The following is a tutorial illustrating how you can use thermal analysis within CATIA V5. MSC.Software’s SimDesigner Thermal (SDT) enables design teams to simulate complex thermal operating environments. This fully integrated and generative solution within CATIA V5 enables the effects of heat transfer, due to conduction and convection, to be simulated and provides users with temperature distributions for subsequent use in structural analysis.

SDT belongs to the MSC.Software SimDesigner for CATIA V5 suite of products and complements the CATIA V5 Analysis portfolio. Please visit the MSC.Software website at: http://www.mscsoftware.com.

This example is part of the SimDesigner for CATIA V5 tutorial. After installing SimDesigner on your computer, select Start, Programs, MSC.Software Corporation, SimDesigner for CATIA V5 Online Docs, User Guide.html. It serves to get you up to speed as quickly as possible on using the product, run a thermal analysis, and perform simple post processing of the analysis results.

Using MSC.Software SimDesigner Thermal (SDT)

Heat Sink Part Example

This example is a thermal analysis of a heat sink used to cool electronic components. The fins on the heat sink help draw heat away from computer chips and other electronic devices. The thermal material properties, thermal loads and boundary conditions used in this example are listed below.

Thermal Conductivity, k -- 240 W/m-K

Specific Heat, Cp -- 0.905 kJ/kg-K

Fixed Temperature -- 395 K

Ambient (Sink) Temperature -- 294oK

Heat Transfer (Film) Coefficient, h -- 237 W/m2-K

Heat Transfer Rate, Q 1W or 1 J/s

Heat Flux (Surface Flux), Q/A -- 90,000 W/m2 -- 200,000 W/m2

All analyses in SDT involve conduction.

Conduction is a mode of heat transfer, or more descriptively, the ability for heat to travel or “flow” through a solid medium (from hot to cold). All heat flow processes involve the leveling of thermal gradients.

Everything is transient in nature, but if left alone long enough, these thermal gradients stabilize and end up in a steady state condition. This first example considers a steady state condition involving pure conduction only.

1. Start CATIA: Select File /Open from the Main Menu and open the following part file located in your installation directory <install_dir>/tutorial/samples/HeatSink.CATpart.

2. Enter SDT: To begin a Thermal simulation you must enter the SDT workbench and set up the thermal loads and boundary conditions and define thermal material properties. From the Start menu pick Analysis & Simulation then select Generative Thermal Analysis. This opens a new CATIA analysis document and puts you in the SDT workbench.

3. Insert a Thermal Case: A Thermal Case is automatically being placed in the specification tree structure on the right of the screen.

4. Define Thermal Material Properties: Right mouse click Isotropic Material.1 in the specification tree, as shown below and select Thermal Material. In the form that appears enter the Thermal Conductivity, k (240 W/m-K) for aluminum.

You may also enter the Specific Heat, cp (0.905 kJ/kg-K).

These two material properties are as important to thermal analysis as Young’s modulus and Poisson’s ratio are to structural analysis. The thermal conductivity represents how well a material allows heat to flow through it. For example, metals conduct much better than, say wood or plastic. This is why you would rather have a wooden or plastic handle for a spatula than a metal one.

The specific heat is a property that represents how fast heat can flow through a particular material and is mainly important for transient effects and does not concern us for steady state behavior, but will be used later in a transient heat transfer analysis.

At this point you should see a Thermal Material.1 entry under the Materials.1 / Isotropic Material.1 in the specification tree to the left side.

5. Apply Fixed Temperatures to Bottom: The analysis will be done by applying a temperature of 395 K on the bottom surface(s) of the heat sink representing the heat from an electronic component and 294 K on some top surfaces of the fins, farthest away from the bottom, representing a cooler outside environment.

Rotate the model until you can see the bottom flat surface. Then drag the Fixed Temperature icon on the right of the screen in the SDT workbench icon toolbar onto the bottom surface of the heat sink.

When you let go of the mouse button the form shown below will appear with the bottom surface selected already as 1 Face. Enter the 395 K temperature and press the OK button.

6. Apply Fixed Temperatures to Fins: Now rotate the model back until you can see the top. Select a few surfaces on the tops of the fins (or all of them if you want) and press the Fixed Temperature icon again. (Multiple selections of surfaces is done by pressing the CTRL key as you select surfaces.)

The form will appear again in which you can now enter 294Kdeg and press OK.

7. Run the Analysis: At this point you should see your specification tree structure at the left of the screen as such:

You can change anything you like by double clicking on the entity in the specification tree. The appropriate form will appear allowing you to select more entities to add or remove, or change property values.

You have now defined the bare minimum to run a thermal steady state heat transfer analysis. Press the Mesh & Compute icon. A form will appear from which you select All from the pull-down menu and press OK. The model will be meshed and the analysis will proceed.

After meshing and while the job is running a monitoring form appears from which you can see the status of the job. You may abort the job if necessary using the Abort button in case you made a mistake. When this form vanishes, your job is done and you may proceed to viewing the results.

8. View the Results: The results are loaded automatically after the analysis is complete. Press the Generate Image icon, select the Thermal Case Solution, and then select the plot you wish to view (Temperature_Iso) from the form that appears and the temperature distribution fringe plot is automatically posted. You can also see that the plot name appears in the specification tree under Thermal Case Solution. The plot below reflects the temperature distribution when only some of the top fin surface temperatures are fixed. Your plot may be slightly different depending on which surfaces you selected.

You can continue the tutorial and work on the convection and transient thermal functionality of SDT.