Joint Stiffness Analysis and Optimization as a Mechanism for Improving Vehicle Structural Design and Performance

Kiani M., Motoyama, K., Rais-Rohani, M., & Shiozaki, H. (2014). Joint Stiffness Analysis and Optimization as a Mechanism for Improving Vehicle Structural Design and Performance. Proceedings of IMechE, Part D: Journal of Automobile Engineering. Sage Publishing Co. 228(6), 689-700.

Abstract

An approach is presented to evaluate the structural performance of a vehicle model in terms of joint stiffness. Seven major joints on the left and right sides of the vehicle body are identified and each joint is decomposed in the finite element model and assigned a separate set of material properties. By adjusting the elastic modulus of each structural member, the effect of joint stiffness on the full and offset frontal impacts as well as vibration characteristics are examined. Latin hypercube sampling is used in the design of experiments to approximate the acceleration, intrusion distance and fundamental vibration frequencies using full quadratic polynomial response surface models. Through direct differentiation, the sensitivities of crash and vibration responses to joint stiffness are calculated. A constrained multi-objective optimization problem is formulated and solved to improve the structural responses by adjusting stiffness at each joint. Evaluation of the car body structure based on optimum joint stiffness showed superior performance relative to the baseline model without weight penalty. The results of both the sensitivity analysis and design optimization are presented and discussed.