Expanded Polypropylene (EPP) - A Global Solution for Pedestrian Safety Bumper Systems

The paper outlines some novel approaches to designing pedestrian safe bumper systems using expanded polypropylene, EPP. Traditional advantages of EPP, such as multiple impact performance and resilience are evaluated in the light of compatibility between conflicting impact requirements. The performance criteria of pendulum, insurance and pedestrian impacts are met by integrating the absorber into the complete energy management system and by the optimisation of the EPP design and density. The necessary packaging space remains minimal through the efficient use of the strain characteristics of EPP. Concept ideas related to fore/aft dual density as well as geometry-based dual-density are outlined. The concepts, developed and tested on a full car system, illustrate how soft initial contact can be combined with a high energy absorbing capacity.