Car Optimization Example

1. Car Optimization Example David Rosen Georgia Tech

2. Optimization Example • Optimization of car body for: • noise-vibration-harshness (NVH) and • crash test (roof crush during roll-over) • 1999-2000 • SGI Origin 2000 supercomputer with 256 processors • 3 days of computer time “Optimization of car body under constraints of noise, vibration, and harshness (NVH) and crash,” J. Sobieszczanski-Sobieski, S. Kodiyalam, and R.J. Yang, Structural and Multisciplinary Optimization, 22, 295-306, 2001.

3. Noise, Vibration, Harshness • Investigate body’s vibration responses, stiffnesses. • Body-In-Prime – body structure and glass (no doors, hood, trunk). • # Element = 68,000, # Nodes = 69,000 • 30 design variables (thicknesses, stiffnesses of joints)

4. Crash Simulation • Roof crush during simulated roll-over. • Body-in-prime + doors • # Elements = 127,000 • 20 design variables

5. Results • 72 hours+ CPU time on SGI Origin. • Mass reduced by 15 kg (1255 to 1240 kg) • Natural frequency increased by ~10% (target) • Stiffnesses improved 5 – 15% • Roof crush resistance improved 15% • Figure shows roofcrush after optimization

6. Initial Cycle 1 Cycle 2 Xlower Xupper Design Variables Thicknesses