Kinematics of inboard-leaning occupants in frontal impacts

Abstract

Objective: Up to one-half of drivers swerve before a crash, which may cause vehicle motions that displace an occupant from a normal seated position. How these altered postures affect occupant restraint in a crash is unknown. The goal of this study was to quantify the effect of an initial inboard lean on occupant kinematics in a frontal impact.

Methods: 30 km/h frontal impact tests were performed with three postmortem human subjects (PMHS) seated in a neutral, upright posture and in a 20° inboard-leaning posture identified from simulated swerving tests with human volunteers.

Results: In comparison to the upright posture, the inboard-leaning posture increased the initial distance from the D-ring to the belted shoulder by 105-156 mm. In the inboard-leaning tests, the occupant’s head displaced 45-70 mm farther forward than in the upright tests and was also located 123-147 mm farther inboard at the time of maximum forward excursion. The peak resultant velocity of the occupant’s head relative to the vehicle interior increased 1.40-1.54 m/s in the inboard-leaning tests.

Conclusions: The posture-induced increase in the distance between the D-ring and the shoulder permitted the increased maximum forward head displacement and increased maximum head resultant velocity relative to the vehicle interior. Thus, an initial inboard lean in a frontal impact may increase the risk and severity of a head strike to the vehicle interior, and alter the location, timing, and nature of airbag engagement.

Keywords:

• Out of position
• cadavers
• occupant kinematics
• front impact

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Joyson Safety Systems provided a grant, restraint components for tests, and guidance to support this study. The authors thank Thomas Seacrist and Christine Holt for analyzing and interpreting the volunteer test data to guide the PMHS initial placement. The authors thank Brian Overby, Sara Heltzel Sochor, and Kevin Kopp of the University of Virginia Center for Applied Biomechanics for their assistance in the design, execution, and analysis of the PMHS tests performed for this study. The authors also thank Maika Katagiri of Joyson Safety Systems for reviewing this manuscript.