Multidisciplinary design optimization of lightweight carbody for fatigue assessment

Abstract

A multidisciplinary design optimization method of a lightweight car body for fatigue life prediction is presented in an attempt to minimize the coupling vibration interactions at different structural frequencies. A mathematical model is developed to simulate such coupling vibration interactions based on the theory of finite elements. The finite element model is integrated with a rigid-flexible coupled multibody dynamics model which was used to obtain load time histories. The obtained results demonstrate the effectiveness of the proposed approach in simultaneously attenuating the structural coupled vibration and improving the durability at several structural frequencies. The field structure dynamics stress verification is carried out and vehicle vibration characteristics are obtained under different operated vehicle speed. The measured dynamic stress is found to be in good agreement with the predictions of the mathematical model. Finally, the fatigue life prediction results of the weight-reduced car body structure before and after multidisciplinary optimization are compared and analyzed. The results also illustrate the multidisciplinary design optimization method can be applied in the durability design of railway vehicle critical structure components when subjected to complex loading environment.

Keywords

• Multidisciplinary design optimization
• Multi-body dynamics
• Finite element method
• Multi-objective optimization
• Fatigue life