ME-430 INTRODUCTION TO COMPUTER AIDED DESIGN TRANSIENT and STEADY STATE THERMAL ANALYSIS OF HEATSINK Pro/ENGINEER and Pro/MECHANICA Wildfire 2.0 Dr Herli Surjanhata Background A steady state thermal analysis calculates effects of constant thermal loads on a model and is used to determine temperatures, heat flow rates, and the heat fluxes in a part A steady state analysis is commonly used as a precursor to a transient thermal analysis to determine the initial conditions A transient thermal analysis is used to determine the temperature, heat storage and other thermal quantities in a model due to a time varying load Because the applied load may be time dependent, the solution is time dependent All other considerations such as the type of the thermal load and the modes of heat transfer are the same as in a steady state analysis Transient analysis is probably the most common form of thermal analysis Problem Statement An engineer must attach copper heat sink to a CPU The heat sink will be subjected to a time varying 50 Watt load and a constant convection of 100W/mC The time required to reach steady state will be determined A fringe plot of the temperature distribution after 1000 seconds will be made Create the Heat Sink Part Create a new part called heat_sink.prt Edit -> Setup -> Units Select Meter Kilogram Second (MKS) in the Units Manager dialog box Click on Set button Choose Interpret dimensions OK -> Close to close the Units Manager dialog box Create a block 0.062 m width X 0.08 m depth x 0.04 m height Extrude both sides Make a cut with the dimensions shown below Pattern the cut with increment of 0.004 m and total of 15 cuts Create a cut to accommodate the fan at the top of the heat sink Create another cut to facilitate the installation clamp The dimensions of the cut are shown below The final part is shown in the following figure Transfer the Model to Pro/MECHANICA From Applications pull-down menu select Mechanica Make sure the Units are correct, then click the Continue button For Model Type, choose Thermal Click the OK button Create a Surface Region On the top of CPU, the size of area in direct contact with the heat sink when the heat sink is installed is 0.012 m x 0.012 m This contact area is situated in the middle of the bottom surface of the heat sink To apply the heat source in this contact area, a surface region should be created From Insert pull-down menu, select Surface Region the Create a Simulation Surface Or click on Region button on the right toolbar Sketch -> Done Pick the bottom surface of the heat sink as sketching plane Select Right under SKET VIEW, and pick RIGHT datum plane as a horizontal or vertical reference for sketching Make sure to include FRONT datum plane as additional reference Create two centerlines to ensure the symmetry, then create a square with 0.012 as the sides Click When prompted with Select surface or surfaces to be split, Select surface to add, pick anywhere on the surface (bottom surface of the heat sink) OK -> Done -> OK to complete the surface region creation Assign Material to the Part From Properties pull-down menu, select Materials Or click the Define Material button from the right toolbar Assign CU as the material of the heat sink Assign -> Part Pick the heat sink Click the OK button Click the Close button Generate the Elements Using AutoGEM The model can be autogemmed during the run, or before the run, if materials have been assigned Select AutoGEM -> Create Or click the Create p-mesh for Geometric Element Modeling button 10 23 Click on Enter the Name of max_dyn_temp Type in the Title of Graph of Max Dynamic Temp Under Display type, select Graph Select Measure in the Quantity box Click on 24 Select max_dyn_temperature Click on OK Click on OK in the Result Window Definition dialog box View -> Display Or click on toolbar in the Select max_dyn_temp Click on OK 25 File -> Exit Results Click on Yes button Type in File Name: transient for the results to be saved OK 26 Click the Close button Save the model Steady State Thermal Analysis Expand the Loads/Constraints in the Model Tree until you see HeatLoad1 Left-click HeatLoad1, then right-click it Select Edit Definition Uncheck Time Dependent option, and click OK -> Done 27 Create a Steady State Thermal Analysis From Analysis pull-down menu, select Mechanica Analyses/Studies From File pull down menu, select New Steady State Thermal 28 Name the analysis as Steady_State Convergence Method: Multi-Pass Adaptive Set the Maximum Polynomial Order to Convergence: Local Temperatures and Local Energy Norms % OK With the Name Steady_State highlighted, run the analysis by clicking Click Yes Click status to check the analysis 29 When the run is completed without error Close the window Close the Analyses and Design Studies dialog box Review the results Click Create a Temperature Fringe Plot 30 Enter Window Name as “temp_steady” for temperature distribution Enter Title “ Steady State Temperature Fringe Plot of Heat Sink” Make sure you fill in the following form (window) as shown below: Click Display Options Check on Continuous Tone Check on Show Element Edges Un-check Show Loads and Show Constraints Click the OK and Show button 31 32 Create a Capping Surface Display Turn off Show Element Edges, and display the heat sink in default orientation Insert -> Cutting/Capping Surfs… Under Type, select Capping Surface OK 33 To delete Capping Surface display, select Edit -> Delete Capping Surface Create a Maximum Temperature Convergence Graph Click on to copy the definition Fill in the Result Window Definition dialog box as shown below 34 Click on OK button Display the maximum temperature convergence graph by selecting View -> Display, and select conv 35 to copy the definition Fill in the Result Window Definition dialog Click on box as shown below Click on OK button Display the maximum temperature convergence graph by selecting View -> Display, and select flux 36 Save the all result windows -> and also Save the model before exiting Pro/ENGINEER 37 ... “ Temperature Distribution of Heat Sink” Under Design Study and Analysis, make sure that Transient_ Analysis is selected Note that Transient_ Analysis is the name of analysis previously given Click... option, and click OK -> Done 27 Create a Steady State Thermal Analysis From Analysis pull-down menu, select Mechanica Analyses/Studies From File pull down menu, select New Steady State Thermal. .. Transient Thermal Analysis Create a transient thermal analysis with Single-Pass Adaptive convergence method For some runs, the Quick Check convergence method may be used to get a quick reading of the