Glass fiber reinforced bumper beams are being used on increasingly more automobiles due to the weight and energy management advantages the materials have over steel. Current bumpers are manufactured using basically three fiber orientations or combinations thereof:
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1)
Random, chopped and continuous
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2)
Unidirectional, continuous along the length of the beam
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3)
0.90, continuous on the length and perpendicular, woven
For the purpose of this paper, the composite used for all FEA models and sample moldings is a 40% continuous glass fiber reinforced, polypropolene resin based, sheet stampable thermoplastic. It is possible to assume that the results can be generatalized to other composites.
The finite element analysis found that significant increases in performances were achieved over the conventional fiber orientations. The ±45° fiber orientation over the entire beam showed the greatest improvement in stiffness over the random orientation, however, this was not considered the optimal result due to manufacturing difficulty discovered in sample molding. The computer modeling was performed using ABAQUS software. The model used is a half model with dimensions similar to that of a bumper for a 3000 pound car. The samples molded for correlation were formed in a “C” section test tool modified to have the same proportions as the FEA model.
The automotive industry continues to demand quality and performance improvements. In order to supply higher performance parts we must not be content with current designs and technology, but must continue to maximize the quality and performance not only of materials but design.