Identification of head injury mechanisms of a child occupant in a child restraint system based on side impact tests

Yoshida, Ryoichi; Okada, Hiroshi; Nomura, Mitsunori; Yokohashi, Matsuto; Fujii, Chikayo; Mizuno, Koji; Yonezawa, Hideki; Tanaka, Yoshinori; Hosokawa, Naruyuki; Matsui, Yasuhiro

Affiliations

³National Traffic Safety and Environment Laboratory, Japan

Abstract

Accident data show that injury risks to children are high in side collision accidents. According to in-depth accident analyses of children seated in forward facing (FF) child restraint systems (CRSs), the head was the most frequently injured body region, and main sources of head injuries were the rear door and side window glass. There are many research studies on child occupant safety in side impacts. However, a review of previous studies of both vehicle-to-vehicle tests and sled tests found that the child head remained in the CRS shell and that the observed severe head injuries in the accident data were not reproduced in the tests. In the present study, a sport utility vehicle (SUV)-to-small car oblique side crash test and sled tests were conducted using a Q3s dummy in the FF CRS to find causes of head contacts which occur frequently in side collision accidents.

In the SUV-to-small car oblique side crash test, a Q3s dummy was seated in the FF CRS installed in the rear seat on the struck side of the small car. The CRS harness was given a slack of 75 mm beforehand. The SUV impacted the rear door of the target small car at an angle of 45 degrees so as to apply a large crash loading on the child dummy. During the crash and up to 65 ms, the vehicle velocity change in the longitudinal direction was comparable to that in the lateral direction. The velocity in the lateral direction continued to increase due to car yaw rotation and reached a peak of 10.5 m/s. This velocity-time history affected the Q3s dummy kinematic behavior. The Q3s dummy moved in an oblique direction and then laterally, and made contact with the side window at 6.8 m/s and the resulting HIC was 702. This test result demonstrates that a forward component of vehicle velocity change and CRS harness slack are factors that may lead to the head making contact with the vehicle interior, thereby resulting in causing serious injuries.

Sled tests were conducted by using a test apparatus specially designed to reproduce the Q3s dummy kinematic behavior in the SUV-to-small car crash test. The factors which were determined to reproduce Q3s dummy kinematic behavior in SUV-to-small car side crash test included the relative location between the test seat and door, the velocity-time history of the car in the longitudinal and lateral directions, the vehicle roll angle during impact, and the contact characteristics between the door and the dummy.

From this study, the hard contact between the child head and the vehicle interior that occurs frequently in side collision accidents was reproduced in a SUV-to-small car oblique side crash test. Factors of a sled test were identified that reproduce the child occupant kinematic behavior in the SUV-to-small car side crash test. The results of this study will be useful for determining the sled test conditions of a CRS side impact, which will be effective in reducing child head injuries.

Links

URL: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv22/22ESV-000066.pdf

Cited Works (5)

Year	Entry
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Cited By (1)

Year	Entry
2013	Tanaka Y, Hosokawa N, Yamaguchi D, Matsui Y. Research of CRS side impact test procedures using an acceleration type sled system. In: Proceedings of the 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 27-30, 2013; Seoul, South Korea.