Engineering thermoplastics are commonly used in the automotive industry as a replacement for steel bumper systems. As the usage of thermoplastics expands in this and other applications, it becomes increasingly desirable to be able to perform preliminary feasibility studies that estimate the performance of the plastic part before tooling is cut. Hence, a study was conducted by GE Plastics in order to correlate the predicted performance of thermoplastic bumper designs via hand calculations and detailed finite-element analyses with results of physical testing. Actual injection-molded thermoplastic bumper beams of a Polycarbonate-Polybutylene Terephthalate alloy were used.
This paper will describe the steps used in bumper design, beginning with hand calculations and detailed finite-element analysis, compare the results obtained to actual physical testing, and make recommendations on techniques for use in future feasibility studies of thermoplastic bumper systems.