Evaluation and Comparison of Thoracic Injury Risk for the Hybrid III and THOR 50th-Percentile Male Anthropomorphic Test Devices in the Rear Seat during Frontal Impacts

Abstract

The objective of this study was to evaluate the thoracic response and injury metrics of the Hybrid III (HIII-50M) and Test device for Human Occupant Restraint (THOR-50M) 50th-percentile male Anthropomorphic Test Devices (ATDs) during frontal, rear-seated sled tests using modern vehicles with various rear seat characteristics. Test bucks were fabricated from seven vehicles (two sedans, three midsize sport utility vehicles [SUVs], one SUV, and one minivan) that represented varying levels of rear seat designs and safety technologies, e.g., three vehicles had advanced restraints with pretensioners (PT) and load limiters (LL). Twenty-four frontal sled tests were conducted using three sled pulses derived from the vehicle-specific New Car Assessment Program (NCAP) crash pulses (NCAP85 Delta V = 56 kph, Scaled Delta V = 32 kph, and Generic Delta V = 32 kph). The HIII-50M and THOR-50M ATDs were positioned in the right and left rear seats, respectively. Maximum chest acceleration (3 ms clip), maximum chest deflection, and deflection-based thoracic injury risk were quantified for both ATDs. For the HIII-50M, the maximum chest acceleration was below the injury threshold (60 g) for all Scaled and Generic tests, but above the threshold during one NCAP85 test with conven-tional restraints. The THOR-50M maximum chest acceleration was below the injury threshold for all tests. The HIII-50M Abbreviated Injury Scale (AIS)3+ maximum sternum deflection injury risk threshold was exceeded or nearly exceeded during the NCAP85 tests for three vehicles, none of which had advanced restraints. The THOR-50M AIS3+ maximum chest deflection injury risk threshold was exceeded during the NCAP85 test for one vehicle, which had PT and LL. Although this study indicates that there may be room for improvement with regard to rear-seat occupant protection, it is currently unknown whether or not either ATD provides a realistic kinematic response or injury risk prediction in the rear seat. Future matched postmortem human subjects (PMHS) testing will facilitate the assessment of the biofidelity and injury risk prediction capabilities of these ATDs in the rear seat.