Computer Analysis of Injuries to Rear Seat Child Occupants Restrained Using a Shared Lap/Shoulder Belt

The present study examines the effects of shared lap/shoulder belt use on the safety of rear seat, child occupants during frontal collisions. Using Mathematical Dynamic Modeling (MADYMO) software, a variety of simulated frontal sled tests were conducted. Eighteen simulated crash scenarios were examined. In each of the simulations either a single 6 Yr Hybrid III dummy or two 6 Yr Hybrid III dummies were placed in the rear, center seat position and restrained using a single lap/shoulder belt. Simulated sled test were conducted at change in velocity (ΔV)'s varying from 24 to 56kph, and principal direction of impact force (PDOF)'s varying from -30° to 30°. The peak resultant lap belt loads and lumbar spine loads experienced by each dummy were used to evaluate the relative potential for injury amongst dummies that were either belted alone or in a shared belt. The simulation results showed that, at most of the considered crash speeds and angles, the dummy restrained in its own belt experienced lower forces than did either of the dummies in the shared belt. An analysis of the dummies in the shared belt also supported prior research suggesting that likelihood of injury to a child restrained by a lap belt only is higher than that of a child that is restrained by a combined lap/shoulder belt.