Browse Publications Technical Papers 2020-01-1217

The Effect of Active and Conventional Head Restraints on Front Seat Occupant Responses in 16 km/h Rear Impacts 2020-01-1217

This study assesses front seat occupant responses in rear impacts with active head restraints (AHR) and conventional head restraints (CHR) using field accident data and test data from the Insurance Institute for Highway Safety (IIHS). 2003-2015 NASS-CDS data were analyzed to determine the injury rate in 1997+ model year seats equipped with AHR and CHR. Results indicated that only 3.1% of occupants were in seats equipped with AHR. More than 58% of occupants were uninjured, irrespective of AHR presence. In <24 km/h delta-V crashes, AHRs were 35.6% effective in reducing MAIS 1-2 injury overall and 26.4% in reducing MAIS 1-2 cervical injury. In IIHS 16 km/h rear sled tests, an instrumented BioRID was evaluated on seats with AHR and CHR. The biomechanical responses were analyzed. HIC15 and concussion risk were calculated from head acceleration data. Test data with AHR and CHR were matched by make and model. First, older model seats with CHR were compared to models with AHR. Then, the models with AHR were compared to newer models with CHR. These analyses showed a reduction in head and upper neck responses with AHR compared to prior generation CHR. A further reduction in these responses was observed in newer CHR compared to prior model AHR. Time at head contact was 89.1 ±13.7 ms with older CHR, 62.4 ± 8.7 ms with AHR and 60.6 ± 9.0 ms with newer CHR. The contact duration was however longer with the AHR tests. The average seatback deflection was 13.6 ± 3.6 degrees with older CHR, 12.3 ± 3.0 degrees with AHR and 10.4 ± 3.0 degrees with newer CHR. Similar trends of decreasing concussion risk were observed. However, the risk of concussion was negligible with later models. The results from this study underline continuous improvement in injury mitigation, regardless of head restraint design.


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