Standards to test the aggressiveness of vehicle front end geometry and its relation to pedestrian lower leg and knee injuries have been proposed by the International Standards Organization (ISO). These standards call for the use of a legform impactor designed to meet prescribed performance and physical criteria developed to represent a typical adult lower extremity.

The current effort focuses on developing a legform impactor subsystem to comply with the IS0 standards. It is also the intention of this project to eliminate the necessity ofusing plastically deformable elements. This system is constructed with nonfrangible knee elements and cylindrical segments representing the tibia1 and femoral components. Dynamic deformation of the legform subsystem is separated into isolated bending and shearing responses which can be directly measured. Bending is controlled by a clutch type mechanism which can be easily adjusted for calibration and certification purposes. The shearing characteristics of the legform are defined by viscoelastic elements which allow medial/lateral translation of the lower leg segment relative to the upper leg.

Bench testing has proven that this mechanism is a viable alternative to the current legform impactor designs which use frangible knee elements. Details concerning the design development, calibrationresults and practical testing are included in this paper.