Rearward-Facing Infant Child Restraint Systems with Support Legs in Frontal and Frontal-Oblique Impacts.

Aditya N Belwadi,Declan A Patton,Kristy B Arbogast,Jalaj Maheshwari

doi:10.3390/ijerph182010799

Abstract

Previous studies of support legs in rearward-facing infant CRS models have focused on frontal impacts and have found that the presence of a support leg is associated with a reduction in head injury metrics. However, real-world crashes often involve an oblique principal direction of force. The current study used sled tests to evaluate the effectiveness of support legs in rearward-facing infant CRS models for frontal and frontal-oblique impacts with and without a simulated front row seatback. Frontal and frontal-oblique impact sled tests were conducted using the simulated Consumer Reports test method with and without the blocker plate, which was developed to represent a front row seatback. The Q1.5 anthropomorphic test device (ATD) was seated in rearward-facing infant CRS models, which were tested with and without support legs. The presence of a support leg was associated with significant reductions of head injury metrics below injury tolerance limits for all tests, which supports the findings of previous studies. The presence of a support leg was also associated with significant reductions of peak neck tensile force. The presence of the blocker plate resulted in greater head injury metrics compared to tests without the blocker plate, but the result was non-significant. However, the fidelity of the interaction between the CRS and blocker plate as an adequate representation of the interaction that would occur in a real vehicle is not well understood. The findings from the current study continue to support the benefit of support legs in managing the energy of impact for a child in a rearward-facing CRS.

Highlights

IntroductionSince the introduction of rearward-facing child restraint system (CRS) models, the design has evolved to further maximize the protection afforded
For the flexible anchor infant child restraint system (CRS) without the support leg, peak neck tensile force of the Q1.5 anthropomorphic test device (ATD) slightly exceeded the 20% risk of AIS3+ neck injury tolerance value, which was reduced by 19% to below the neck injury tolerance value scaled from UN ECE R94 when a support leg was used
The presence of a support leg was associated with a negligible decrease and increase in peak neck flexion moments for the Q1.5 ATD in the flexible- and rigid-anchor infant CRS, respectively, all values were well below neck injury tolerance limits

Summary

Introduction

Since the introduction of rearward-facing CRS models, the design has evolved to further maximize the protection afforded. Some European rearward-facing CRS models are designed with a support leg ( referred to as a ‘load leg’) to reduce forward rotation during frontal impacts; this feature has been evaluated in laboratory-based sled tests. Le Claire et al [5] conducted sled tests using the R44 test bench and a vehicle seat to compare rearward-facing CRS models to the same CRS models that were modified to have a support leg. It was found that head acceleration values of anthropomorphic test device (ATD) in the modified rearward-facing CRS models with support legs were reduced compared to the unmodified CRS models for the R44 test bench, but not the vehicle seat. Sherwood et al [6]

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