Nonlinear Dynamic Analysis of an Automotive Knee Bolster System

In the continuing automotive design trends towards greater lightness, the energy absorption capacity and low deformability of the knee bolster system in a front end collision, must not be compromised for light material guages. In order to minimize knee injury to both the driver and the front seat passenger, it is necessary to have a knee bolster system that absorbs as much of the impact energy as possible. Moreover, in order to minimize chest injury to the driver, the driver side knee bolster must not come in contact with the steering column during impact. In a study conducted by us, a simplified approach was used to evaluate the energy absorption capacity and the deformations of the knee bolster system under frontal impact. The analysis was performed using a nonlinear dynamic finite element computer code, DYNA3D, developed at the Lawrence Livermore National Laboratory. The results show that the energy absorption capacity and the amount of deformation of the knee bolster system are dependent on the design of the support brackets.