A Statistical Approach to Design Trim Pillars for FMVSS Extended Head Impact 970162

The passage of FMVSS 201 Extended Rule in November 1993 resulted in the evaluation of a variety of designs and materials for use in the interior trim components such as A and B pillars. Historically these parts had requirements for aesthetics, dimensional stability, and thermal performance. Structural performance with energy absorbing capability to prevent head injury is now a significant addition to these requirements. Visibility concerns limit the amount of packaging space available for implementing countermeasures in this area.

Designing countermeasures by trial and error involves extended development time and significant expenditures. This paper discusses the use of the finite element analysis technique that is being increasingly used to accurately simulate head impact situations. The use of high strain rate material property (true-stress, true-strain curves) data is necessary for dynamic impact simulation analysis. Correlation of the finite element analysis results with actual test data is discussed. Based on this correlation, the paper discusses the use of Design of Experiments (DOE) techniques to optimize the design of the countermeasure. Effects of important design parameters such as material modulus and yield strength, rib spacing, depth and thickness and trim thickness on Head Injury Criteria, HIC(d), maximum acceleration and time interval are discussed.