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Traditional knee bolster designs consist of a first-surface plastic component covered by paint or vinyl skin and foam, with a subsurface steel plate that transfers knee loads to 2 steel crush brackets. The design was developed to meet FMVSS 208 and OEM requirements. More recently, technological developments have allowed for the steel plate to be replaced by a ribbed plastic structure, which offers cost and weight savings to the instrument panel system. However, it is still a hybrid system that combines plastic with the 2 steel crush brackets. This paper will detail the development of an all-plastic design, which consolidates the plastic ribbed reinforcement plate with the 2 steel crush cans in a single engineering thermoplastic component. The new system is expected to offer further cost and weight savings.

In automotive lighting applications, the selection of materials is driven by the temperature to which the material will be subjected during FMVSS or OEM standard testing. This is particularly true of reflectors, for both forward and signal lighting. In general, the effect of material properties upon the maximum temperatures seen in the part is rarely considered. If, for example, a material has a higher thermal conductivity than another, then it may be able to shed more internal heat to the ambient environment, possibly allowing a lower temperature material to be used. Another effect that could be important is the transparency of the material to infrared radiation. This portion of the electromagnetic spectrum will generate most of the heat built up in the material that is caused by radiation, as opposed to convection or conduction.

A previous paper detailed the generation of high strain-rate data (greater than 100%/sec) on engineering thermoplastic materials. These data were used in conjunction with dynamic finite-element analysis techniques to predict the load-deflection response of instrument panel retainers that were impacted with an approximate head form. Correlation between analysis results and physical testing for part stiffness, strength, and ductility were very good for a variety of materials. Use of such data represents a vast improvement in analysis accuracy versus the use of traditional material data in these types of analyses. Methodology for the use of high strain-rate data is explained and demonstrated through this correlation. The technique can be used to evaluate and improve future instrument panel designs. Also, suggestions for further development work in the area of materials models are made.

In past physical testing of thermoplastic bumper beams, a large difference in the performance of the bumper on a test cart versus the actual vehicle was found. This difference was large enough to cause concern over the accuracy of testing on test carts to determine part feasibility. Therefore, it is necessary to determine the effect of rail stiffness on bumper beam performance. For this reason, a previous paper [1] discussed a simple method with which to assess the great effect that rail stiffness can have on bumper beam performance. Currently, the only method available to engineers to account for this effect is to model the rail and support bracket in a complex analysis. This technique is time consuming and difficult to use in the preliminary stages of design when it is preferable to use quick hand calculations to rough out part geometry. It would be desirable to develop a simple method to approximate the stiffness of rails in calculations that entail varying degrees of complexity.