The design optimization of the Cowl cross bar - The light Cowl cross bar satisfying 5 performances

摘要

Nowadays, more lightweight designs is the key goal of all major automotive industries, and they are always looking for more mass saving design. One of the main sections for more lightweight automotive area is the Cowl cross bar(CCB) assemblies. A cowl-ross bar or cross-car beam supports a steering system, airbag module, audio, Instrument panel and air conditioning system. The CCB integrates these components into the cockpit module and connects to the body. So the CCB must meet the 5 performance requirements, ①NVH requirement to minimize the vibration of the steering wheel, ②Crash performance for less deflection in various impact conditions, ③Steering response requirement for better steer predictability, ④Durability performance like the fatigue life of the brackets supporting the safety parts, and ⑤Supporting-rigidity for the components of the cockpit module. In this study, a new methodology for the design optimization of CCB assemblies is proposed to obtain a more lightweight design considering 5 targeted requirements. At first, for NVH and Steering response performance, 3-steps of optimization was fulfilled in sequence of (1) Size Optimization (thickness, diameter) and mounting position, (2) Case studies about the various types of brackets and (3) Shape optimization that is reinforcing locations with high element density and eliminating those with density lower than the threshold value using the topology and topography. The proposed design and optimization framework was verified whether it could meet the crash, durability and stiffness requirements. The final optimal CCB would be applied to the new platforms of the Hyundai-Kia motors.