Design Optimization Using SDRC/I-DEAS and GENESIS Structural Analysis and Optimization Software

1. Name: Dipankar Ghosh, Ph.D. Company: VR&D, Inc. Session # (SIM085) Performing Design Optimization Using SDRC/I-DEAS and GENESIS Structural Analysis and Optimization Softwareby Dipankar GhoshChristophe CharpentierIku Kosaka

2. Outline • Introduction • Objective • GENESIS Structural Analysis and Optimization Software • SDRC/I-DEAS • GENESIS-SDRC/I-DEAS Interface • Design Example

3. Introduction • Optimization technology is widely acknowledged in engineering, but not widely used • Reasons: • Difficulty in creating design data • Lack of time to educate engineers to perform optimization • Lately, there has been some pressure to reduce the “time-to-market” • This is an opportunity for software developers like us, and provide easy to use design tools

4. Introduction • Recent Efforts: • FEMB (ETA) & Msc.Patran can be used as pre- and post processors for GENESIS Structural analysis and optimization • Msc.Patran can be used with Msc.Construct to perform topology optimization • HyperMesh (Altair Engineering) can be used with OptiStruct to perform topology optimization

5. Objective • Develop a unified design tool, including drafting, pre-post processing, for both analysis and design optimization using SDRC/I-DEAS and GENESIS • Allow not only CAE designers but also CAD designers to modify their designs in a systematic manner • Demonstrate the design process using the tools developed here

6. GENESIS Software • GENESIS is a fully integrated structural analysis and design optimization software • Created from the very beginning as a design software, as opposed to adding optimization to an analysis program • Uses second generation approximation concepts and well established optimizers for faster convergence and efficient/robust performance

7. GENESIS Software • Analysis: • finite element method (FEM) • static, normal modes, direct and modal frequency analysis, heat transfer, and system buckling • Design optimization: • Shape, sizing and topology optimization

8. GENESIS Software • Typically requires < 10 detailed FEAs, even for large and complex design tasks • No special knowledge of optimization technology is required! • Input data deck is similar to NASTRAN data deck • NASTRAN deck is easily converted to GENESIS deck, and then solve it using GENESIS

9. GENESIS Software • Special Features: • To create smooth variations of structural dimensions and shapes, semi-automatic DOMAIN elements are used • Use topology optimization (material layout) for preliminary design, and refine it later using shape and sizing optimization • BIGDOT Optimizer - allows 1000s of design variables

10. SDRC/I-DEAS • Computer-aided design tool • Drafting, analysis and optimization • Analysis options: • linear statics, normal mode, constrained mode dynamics, buckling, heat transfer, potential flow, and nonlinear statics • Only linear statics and normal mode analyses can be used in optimization.

11. SDRC/I-DEAS • Optimization can be performed using CAD parameters • Still optimization is limited to entry level optimization • Limited responses • Only shape and sizing optimization • No topology optimization • The present development is intended to cover optimization, both entry level and high end capabilities

12. Interface Details • GENESIS and I-DEAS are stand alone programs • Make use of Open I-DEAS • Interface can access FEM data and pre- and post processing capabilities of I-DEAS • GENESIS specific data is stored in I-DEAS’s database

13. Interface Details

14. Overall Methodology • Steps: • Start with a design space, perform topology optimization to come up with optimal design space • Interpret the topology results, create the FEA model for shape/sizing optimization • perform shape/sizing optimization with detailed design specifications

15. Design Example • Topology Optimization • A bracket used to attach a strut to a rail • Minimize global strain energy • subject to material constraint • Mass fraction • Retain 30%, 50%, 70% mass

16. Design Example • Create topology data

17. 70% material 50% material 30% material Design Example • Topology results

18. Design Example • Topology results • Candidate design for shape and sizing optimization • Generate CAD (lines and surfaces) • Create FEA model for shape/sizing optimization Side View Front View Isometric View

19. Design Example • Topology results • Took out about 30% of the material • Structural performance was not degraded much

20. Design Example • Realization of topology optimization Isometric View Front View Side View

21. Design Example • Shape and Sizing Optimization • More detailed and complete design • Multiple load cases • Point load • Natural frequency • Objective function: mass (minimize) • Constraints: • Von Mises stress < 200 MPa • Fundamental frequency > 850 Hz

22. Design Example • Shape Optimization • DOMAINs QUAD4 and TRIA3 Domains with DVGRIDCs HEXA Domain with DVGRIDCs

23. Design Example • Perturbation (DVGRIDC) vectors are governed by 8 design variables

24. Design Example • Create DOMAINs

25. Design Example • Create DVGRIDCs

26. Design Example • Shape optimization results • design variables reached the side constraint values • Further weight reduction is possible • While expanding bounds, make sure mesh is not distorted

27. Design Example • Shape optimization results Final design for shape optimization Initial design for shape optimization

28. Conclusions • A tool to interface GENESIS with I-DEAS has been presented • I-DEAS users now have access to GENESIS analysis and optimization capabilities • Users can perform a wide range of structural optimizations using these tools