In previous studies, foam materials have been used as the energy absorbing structure on automobile bumpers to reduce the severity of leg injuries in pedestrian~to­ automobile accidents, One obvious problem, with the foam material is that some portions of the foam remain uncrushed even though being fully compressed. To ensure effective impact absorbing performance while reducing the space required for the bumper, the portions remaining uncrushed must be minimized, In other words, crush efficiency, defined as the quotient obtained by dividing the crushed length by the original length prior to impact, should be improved.

This report describes the results of research using a skin only bumper structure with high crush efñciency. The results were applied to the Honda ASV-3, a research vehicle developed as a part of the Advanced Safety Vehicle (ASV) project.

Lateral knee bending angle, knee shearing force and force acting on the tibia were adopted as leg injury parameters. Based upon these parameters, a vehicle front profile which might reduce the parameters, was studied and assessed using computer simulation. Computer simulations were performed to ensure the effectiveness of the skin only bumper structure. The structure effectiveness was confirmed in reducing leg injury parameters with impact tests using a rigid legform impactor and a pedestrian dummy.