ANSYS Advanced Analysis Techniques Guide

1 ANSYS Advanced Analysis Techniques Guide ANSYS Release 002184. August 2005. ANSYS , Inc. and ANSYS Europe, Ltd. are UL. registered ISO. 9001:2000. Companies. ANSYS Advanced Analysis Techniques Guide ANSYS Release ANSYS , Inc. Southpointe 275 Technology Drive Canonsburg, PA 15317. (T) 724-746-3304. (F) 724-514-9494. Copyright and Trademark Information 2005 SAS IP, Inc. All rights reserved. Unauthorized use, distribution or duplication is prohibited. ANSYS , ANSYS Workbench, CFX, AUTODYN, and any and all ANSYS , Inc. product and service names are registered trademarks or trademarks of ANSYS , Inc.

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4 The ANSYS . third-party software information is also available via download from the Customer Portal on the ANSYS web page. If you are unable to access the third- party legal notices, please contact ANSYS , Inc. Published in the Table of Contents 1. Design Optimization .. 1 1. Getting Started with Design Optimization .. 1 1. Design Optimization Terminology .. 1 1. Information Flow for an Optimization Analysis .. 1 3. Optimizing a Design .. 1 3. Create the Analysis File .. 1 4. Build the Model Parametrically .. 1 5. Obtain the Solution .. 1 6. Retrieve Results Parametrically .. 1 6. Preparing the Analysis File.

5 1 7. Establish Parameters for Optimization .. 1 7. Enter OPT and Specify the Analysis File .. 1 8. Declare Optimization Variables .. 1 8. Choose Optimization Tool or Method .. 1 9. Specify Optimization Looping Controls .. 1 10. Initiate Optimization Analysis .. 1 11. Review Design Sets Data .. 1 12. Manipulating Designs Sets .. 1 13. Multiple Optimization Executions .. 1 13. Restarting an Optimization Analysis .. 1 13. Optimization Mehods .. 1 14. Subproblem Approximation Method .. 1 15. Approximations .. 1 15. Conversion to an Unconstrained Problem .. 1 15. Convergence Checking .. 1 16.

6 Special Considerations for Subproblem Approximation .. 1 16. First Order Method .. 1 17. Convergence Checking .. 1 17. Special Considerations for the First Order Method .. 1 18. Random Design Generation .. 1 18. Using the Sweep Tool .. 1 18. Using the Factorial Tool .. 1 19. Using the Gradient Evaluation Tool .. 1 19. Guidelines for Choosing Optimization Variables .. 1 20. Choosing Design Variables .. 1 20. Choosing State Variables .. 1 21. Choosing the Objective Function .. 1 22. Hints for Performing Design Optimization .. 1 22. Generating the Analysis File .. 1 22. Fixing Design Variable Values After Execution.

7 1 23. Modifying the Optimization Variables After Execution .. 1 24. Local Versus Global Minimum .. 1 24. Minimum Weight Versus Minimum Volume .. 1 24. Mesh Density .. 1 25. Using Substructures .. 1 25. Sample Optimization Analysis .. 1 25. Problem Description .. 1 25. Problem Specifications .. 1 25. Using a Batch File for the Analysis .. 1 25. Using the GUI for the Analysis .. 1 27. ANSYS Advanced Analysis Techniques Guide . ANSYS Release . 002184 . SAS IP, Inc. ANSYS Advanced Analysis Techniques Guide Where to Find Other Examples .. 1 30. 2. Topological Optimization .. 2 1. Understanding Topological Optimization.

8 2 1. Employing Topological Optimization .. 2 2. Define the Structural Problem .. 2 2. Select the Element Types .. 2 2. Specify Optimized and Non-Optimized Regions .. 2 3. Define and Control Your Load Cases or Frequency Extraction .. 2 3. Linear Structural Static Analysis .. 2 3. Modal Analysis .. 2 4. Define and Control the Optimization Process .. 2 4. Defining Optimization Functions .. 2 5. Defining Objective and Constraints .. 2 5. Solving and Initializing Optimization .. 2 6. Executing a Single Iteration .. 2 7. Executing Several Iterations Automatically .. 2 8. Review the Results .. 2 8.

9 A 2-D Multiple-Load Case Optimization Example .. 2 9. Problem Description - First Scenario .. 2 9. Problem Results -- First Scenario .. 2 11. Problem Description -- Second Scenario .. 2 12. Problem Results - Second Scenario .. 2 13. A 2-D Natural Frequency Maximization Example .. 2 15. Problem Description .. 2 15. Problem Results .. 2 17. Hints and Comments .. 2 19. 3. Probabilistic Design .. 3 1. Understanding Probabilistic Design .. 3 1. Traditional (Deterministic) vs. Probabilistic Design Analysis Methods .. 3 2. Reliability and Quality Issues .. 3 3. Probabilistic Design Terminology.

10 3 3. Employing Probabilistic Design .. 3 7. Create the Analysis File .. 3 8. Sample Problem Description .. 3 9. Build the Model Parametrically .. 3 9. Obtain the Solution .. 3 10. Retrieve Results and Assign as Output Parameters .. 3 10. Prepare the Analysis File .. 3 11. Establish Parameters for Probabilistic Design Analysis .. 3 11. Enter the PDS and Specify the Analysis File .. 3 12. Declare Random Input Variables .. 3 13. Visualize Random Input Variables .. 3 18. Specify Correlations Between Random Variables .. 3 18. Specify Random Output Parameters .. 3 21. Choose a Probabilistic Design Method.