Tyan, T., Vinton, J., Beckhold, E., Zhang, X. et al., "Modeling of an Advanced Steering Wheel and Column Assembly for Frontal and Side Impact Simulations," SAE Int. J. Mater. Manf. 7(2):366-401, 2014, doi:10.4271/2014-01-0803.
This paper presents the final phase of a study to develop the modeling methodology for an advanced steering assembly with a safety-enhanced steering wheel and an adaptive energy absorbing steering column. For passenger cars built before the 1960s, the steering column was designed to control vehicle direction with a simple rigid rod. In severe frontal crashes, this type of design would often be displaced rearward toward the driver due to front-end crush of the vehicle. Consequently, collapsible, detachable, and other energy absorbing steering columns emerged to address this type of kinematics. These safety-enhanced steering columns allow frontal impact energy to be absorbed by collapsing or breaking the steering columns, thus reducing the potential for rearward column movement in severe crashes. Recently, more advanced steering column designs have been developed that can adapt to different crash conditions including crash severity, occupant mass/size, seat position, and seatbelt usage. These advanced steering columns incorporate adaptive features, mechanically or pyrotechnically activated, to add flexibility in absorbing impact energy of different levels. In addition to complying with safety regulations for steering columns (e.g., FMVSS 203 and 204), these advanced steering column designs are able to handle different load conditions. These load conditions range from high impact loads for larger and unbelted dummies in severe crash tests to low impact loads for small and belted dummies in lower severity crash tests, as required by FMVSS 208 and NHTSA's NCAP safety rating system. The modeling of a steering assembly with advanced safety features becomes more challenging as the steering column designs become more complex.In the final phase of the study, the focus is the modeling of an advanced steering wheel and column assembly that can be used in frontal and side impact simulations. In the first phase of the study, ten component and subsystem tests were conducted to develop the modeling methodology of an adaptive energy absorbing steering column assembly. Three steering wheel assembly tests and eight steering wheel and column assembly tests, with the steering column being mounted in normal and offset angles, were developed and conducted in the final phase of the study. In addition, various dynamic impact speeds, including quasi-static, were considered so that speed sensitivity of the steering wheel and column assembly could be obtained. The final modeling methodology of the steering wheel and steering column assembly is developed based on reasonable correlation achieved with twenty one tests. The developed modeling methodology can be applied to other advanced steering wheel and column assemblies and will enhance evaluation of occupant responses in full vehicle or subsystem simulations. It can also be used in finite element analysis programs (LS-DYNA) and/or coupling of finite element and occupant analysis programs (LS-DYNA & MADYMO coupling). The final goal of this study is to utilize the developed modeling methodology in vehicle development to occupant safety systems, optimize prototype testing and enable faster development cycle time.