Assessment of pedestrian head impact dynamics in small sedan and large SUV collisions

Abstract

This study compares head impact dynamics between post-mortem human surrogates (PMHS) and the Polar-II pedestrian crash dummy in vehicle–pedestrian impacts with a small sedan and a large sports utility vehicle (SUV). A total of 15 (8 sedan and 7 SUV) full-scale vehicle pedestrian impact tests were performed at 40 km/h. For each vehicle, two (SUV) or three (sedan) PMHS tests and five dummy tests were performed, with three of the dummy tests in the same configuration to show repeatability, and the other two tests utilising slightly different configurations. Head linear and angular kinematics were captured from PMHS and dummy head instrumentation, and dummy upper neck load cell data were used to determine neck forces and calculate head impact forces. Differences in head impact locations, timing and kinematics between the dummy and PMHS were minimised when the dummy was positioned higher above the ground reference level to match the pelvis height of the PMHS. On average, the dummy recorded higher resultant impact forces (2930 N vs. 1862 N) in windshield impacts to the sedan than in hood impacts to the SUV, which resulted in higher 15-ms Head Injury Criteria (HIC15) values and higher peak and averaged angular accelerations. While there are differences in dummy injury risk metrics, both the dummy and PMHS data show that the difference in injury risk metrics predicted by the dummy can be explained by the variation in impact velocity between the sedan (14.1 ± 1.2 m/s) and the SUV (10.7 ± 2.3 m/s), the differences in injury risk predicted by the PMHS are not as clear due to confounding factors. The data and analyses presented in this study also show that neck forces during head impacts contribute a substantial and additive effect to the head impact accelerations (and thus HIC15 values) measured in the dummy, and that for the SUV, neck forces affect head accelerations more than impact forces. Despite analysing only lateral impacts with two vehicle geometries at 40 km/h, this study provides the only comparison of PMHS and dummy pedestrian head impact kinematics data available.