Determination of Bumper Styling and Engineering Parameters to Reduce Pedestrian Leg Injuries

The European Commission is proposing legislation directed at reducing the severity of injuries sustained by pedestrians in the event of an impact with the front-end of a motor vehicle. One aspect of this proposed legislation is reducing the pedestrian's leg injuries due to contact with the bumper and frontal surfaces of a vehicle, assessed using a 'pedestrian leg impact device' or 'leg-form.' This legislation also presents the challenge of designing a bumper system which achieves the required performance in the leg-form impact, without sacrificing the bumper's primary function of vehicle protection during low-speed impacts. The first step in meeting this challenge, then, is to understand what effects the front-end geometry and stiffness have on the leg-form impact test results. These data will then need to be compared to low-speed impact performance to assess if the 2 requirements are compatible. This paper details an investigation, using concept Finite Element models and a front-end variable geometry vehicle test buck, of the styling and engineering trade-offs for a pedestrian safe bumper system.