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The passing of the federal regulation for head impact protection for upper interior components (FMVSS 201U) has led to the use of a variety of foam materials in interior trim pillar and headliner reinforcement applications. Polyurethane foams and expanded bead foams are some of the commonly used foams in these applications. However, the low energy absorption efficiency (35% - 55%) of the current foams requires the use of 20 mm - 40 mm of packaging space to integrate the countermeasures that make it possible to meet the regulations. A newly developed high efficiency olefin based foam is able to meet the performance requirements at a reduced packaging space. A combination of physical structure and superior mechanical properties provides the much needed higher efficiency (80% - 90%) of the olefinic foam. This paper discusses the foam architecture and performance benefits for many interior applications, such as energy absorbing countermeasures in pillar trim, headliners, and door panels.

Passenger protection to reduce fatality and injury rates is of critical importance worldwide. Side and head impact occupant protection requirements have been legislated both in North America and Europe. Even though the applicable legislation for each impact condition is different, the impact event poses similar functional requirements. Therefore, concept designs and methodologies for engineering optimization can be used interchangeably to develop countermeasures whether dealing with side or head impact crashworthy systems. The present paper outlines the use of a systematic approach that combines structural CAE simulations and Design of Experiments (DOE) for the optimization of the structural performance of crushable thermoplastic energy absorbers that are being used in door panels and upper interior trim. The use of DOE allows the evaluation of critical design and material parameters which affect the performance of the system.

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.

Revisions to the FMVSS 201 head impact legislation have had a significant impact on the design and engineering of upper interior trim components of cars and light trucks. Structural performance with energy absorbing capability to prevent head injury is now a significant addition to these requirements. However, occupant visibility blockage limits the amount of packaging space available for implementing countermeasures in this area. A novel approach to meeting the FMVSS 201 structural requirements, while keeping the interior trim on the vehicle minimally changed, has been developed. This approach requires the use of energy absorbing rib structures sandwiched between the trim panel and the inner body-in-white (B/W) sheet metal in A and B pillars. Heat staking is used to attach the rib structure to the interior trim panel.

Side mirror design optimization has been traditionally accomplished using an iterative design and testing process, often resulting in considerable costs in retooling operations, and causing significant delays in production. The ever increasing demand for high quality products has led major automotive companies to set high performance standards for side mirrors. These include structural, vibration, and aesthetic criteria, which affect the functionality and appearance of the mirror. The first two issues have been successfully addressed here using a fundamental design philosophy and a computer aided engineering approach. This approach has helped improve product quality, reduce the costs associated with redesign and retooling and minimize the development cycle time from concept to production.