Citation

Edwards MA, Jagtap SR, Jermakian JS. 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV); April 3-6, 2023; Abstract #: 23-0173, pp. 25p. Washington, DC USA: US National Highway Traffic Safety Administration, 2023 open access.

Affiliation

Insurance Institute for Highway Safety, USA

Copyright

(Copyright © 2023 open access, US National Highway Traffic Safety Administration)

Abstract

27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years

https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000173.pdf

Rear seat safety advancements have lagged those in the front. To address this gap, this research aimed to develop assessment metrics to evaluate the relative protection provided by rear seat restraint systems across a series of vehicle crash tests. Thirty-two full-scale vehicle crash tests were conducted with a Hybrid III 5th percentile female dummy seated in the left rear seating position in a 64.4 km/h, 40% offset deformable barrier test. Vehicles varied in size, class, and presence of belt pretensioners and load limiters. Dummy injury metrics for the head, neck, thorax, and femur were evaluated along with occupant kinematic metrics including head excursion and submarining. Of the 32 tests, 18 also included a pressure sensor on the rear occupant's thorax to locate the dynamic shoulder belt position. Shoulder belt tensions ranged from 3.4 to 8.3 kN, and higher shoulder belt tensions were generally associated with higher head and neck injury values, but sternum deflection did not show a similar relationship. High (> 40 mm) and low (~20 mm) sternum deflections were observed for vehicles with and without pretensioners and load limiters and for a wide range of belt tensions. Higher dynamic belt positions were correlated with lower chest deflections and compensating for the effect of belt position aligned sternum deflections with expectations based on shoulder belt tensions. Head contact only occurred in one vehicle, but head excursion boundaries in the absence of impact remain important to ensure that restraint systems limit excursion and the risk of head injury for higher severities or larger occupants. The dummy showed propensity for submarining, an important risk factor for abdominal injuries. Femur axial forces were low for all vehicles, even in cases where the knees contacted the front seatback. Assessment metrics were developed to evaluate the relative protection of rear occupants across a range of vehicles. A novel dummy-based metric, called the Chest Index, was developed that allows the comparison of chest protection across vehicles with a range of dynamic belt fit.

Language: en