Dynamics of Human Legs Subjected to Posterior Impact

Abstract

This is a dynamic analysis of a three-mass, hinged beam model representing a standing human struck suddenly with a posterior, horizontal, step impact force. The results of parametric studies, presented in terms of nondimensional system variables, show the essential features of the dynamic moment responses in the lower leg. Included are the effects of the distribution of body mass, the location of the impact force, and the base fixity, with and without slip. Closed-form results show that the point of impact is not always the point of maximum bending moment on the lower leg. For step impact loads applied near the knee joint, peak moments are predicted near the midlength of the lower leg, the location coincident with about half of the observed fractures to the tibia and fibula of pedestrians struck by car bumpers near the knees.