1998-02-23

Strength Improvements to Automotive Roof Components 980209

Experimental results from three point bending and axial compression tests of common automotive roof elements are presented. Modifications of these components were also tested to evaluate the effect of structural reinforcements and void filling.Under three-point bending, an open hat section side header (or side rail) was tested and failed in a manner consistent with observed failures in real world accidents. Modifying the hat section to create a closed section increased load capacity and energy absorption, and demonstrated some gains in strength to weight performance. Two epoxy compounds in a similar closed section configuration resulted in substantial increases in peak load, energy absorption and strength-to-weight ratio.In the axial compression tests, a open “c” section front header were tested in axial compression and failed just past a sheet metal reinforcement consistent with observed failures in real world accidents. The void filled header was successful at resisting local section collapse at the sheet metal reinforcement and material holes. Peak axial strength, energy absorption and strength to weight were increased for the void filled header relative to the production component. A metal reinforced front header and a production closed side header from the same vehicle also generated considerable increases in peak strength, energy absorption and strength to weight ratio.Both void filling and structural reinforcements demonstrated structural advantages in peak load capacities and energy absorption properties. Optimization of the proper void filling density and amount of metal reinforcement is required on an individual design basis to maximize the effectiveness. Both techniques demonstrated an ability to improve upon existing automotive components and repair some of their inherent weaknesses.

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