Predicting the Bumper System Response of Engineering Thermoplastic Energy Absorbers with Steel Beams 2002-01-1228

An efficient energy absorber (EA) will absorb impact energy through a combination of elastic and plastic deformation. However, the EA is typically coupled with a steel reinforcing beam, which can also elastically and plastically deform during an impact event. In order to design and optimize an EA/Beam system that will meet the specified vehicle impact requirements, the response of the entire assembly must be accurately predicted.

This paper will describe a finite element procedure and material model that can be used to predict the impact response of a bumper system composed of an injection molded thermoplastic energy absorber attached to a steel beam. The first step in the process was to identify the critical material, geometric, and boundary condition parameters involved in the EA and Beam individually. Next, the two models were combined to create the system model. Actual test results for 8km/hr. FMVSS part 581 impact series and Insurance Institute for Highway Safety (IIHS) test sequences will be presented and comparisons will be made to validate the loads and intrusions predicted by the computer analysis. This validation and correlation of an EA/Beam performance model can provide the ability to reduce development cycle times and costs required to design bumper systems.