1997-02-24

Engineering Development of a Composite Cross Car Beam 970727

The objective of this paper is to discuss the process, from design conception through analytical simulation to experimental test, of the development of a composite cross car beam for a passenger vehicle application. Over the past five years there has been considerable interest in the development of cross car beams, which serve as the main component for support of the Instrument Panel (I/P) structure and related systems. Stringent design requirements for vehicle Noise, Vibration and Harshness (NVH), durability and crashworthiness have driven the role of cross car beams to new levels. In addition, new styling trends, such as cabin forward design, and new vehicle manufacturing and assembly methods, such as cockpit build, have also placed demands on the role of cross car beams.
With an ever-increasing interest to reduce vehicle mass and part count and improve fit-and-finish, integrated structures such as die castings and moldings have replaced traditional structures which feature many fasteners and welds. As a result, innovation in cross car beams has seen various designs such as injection molded plastic, compression molded plastic, and die cast magnesium. While some current production examples of these constructions exist, the requirements for future vehicles continues to increase the demands on cross car beam performance.
This paper will discuss the development of an injection molded composite (glass-reinforced plastic) cross car beam concept which has been packaged for an existing production vehicle and is developed to meet the same functional criteria for NVH, durability and crashworthiness performance as the traditional steel concept currently in production. This composite cross car beam is unique in its application to a cockpit build vehicle, where components of substantial mass, such as the Heating, Ventilation and Air Conditioning (HVAC) system module, steering column and occupant protection system are included. This discussion will document the process from conceptual design, through iterative analytical simulation using Finite Element Analysis for all design conditions, to arrive at a design which compares favorably with the production design of traditional construction technique. The discussion will conclude with plans for experimental test, and will summarize the process and methods used and make recommendations for future development efforts.

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