Bumper Systems Designed for Both Pedestrian Protection and FMVSS Requirements: Part Design and Testing 2004-01-1610

This paper describes a bumper system designed to meet the current FMVSS (Federal Motor Vehicle Safety Standard) and ECE42 legislation as well as the European Enhanced Vehicle Safety Committee (EEVC) requirements for lower leg pedestrian impact protection [1] (The EEVC was founded in 1970 in response to the US Department of Transportation's initiative for an international program on Experimental Safety Vehicles. The EEVC steering committee, consisting of representatives from several European Nations, initiates research work in a number of automotive working areas. These research tasks are carried out by a number of specialist Working Groups who operate for over a period of several years giving advice to the Steering Committee who then, in collaboration with other governmental bodies, recommends future courses of action designed to lead to improved safety in vehicles).

A dual performance car bumper system - 4 km/hr barrier and pendulum combined with lower leg impact protection is achieved through a combination of material properties and design. The difficulty in designing such a system arises from conflicting bumper system requirements. In order to achieve lower leg protection, a relatively soft bumper system is required while a relatively stiff system is typically needed to manage barrier and pendulum impacts.

Using computational analysis modeling, an injection molded energy absorber (EA) (Figure 1) was designed and built to demonstrate the ability to achieve pedestrian protection requirements for knee bending angle, knee shear displacement, and tibia acceleration as well as 4 km/hr pendulum and barrier impacts (ECE42, FMVSS). The energy absorber was also tested to assess 8 km/hr pendulum and barrier impact performance (CMVSS - Canadian Motor Vehicle Safety Standard).

The results demonstrate how an injection molded EA using polycarbonate/polybutyelene terephthalate (PC/PBT) resin (Figure 1) can meet both FMVSS and pedestrian safety requirements and can do so within a packaging space representative of today's vehicle styling (typically 80 to 120 mm).