The influence of asymmetrical lower belt anchorage locations on the crash performance of child restraint systems

Huijskens, C. G.; Janssen, E. G.; Verschut, R.

Affiliations

¹TNO Road-Vehicles Research institute, Crash-Safety Research Centre, Delft, The Netherlands

Abstract

Several field studies have shown that a large percentage of child restraint systems (CRS) are used incorrectly. This is not only due to the sometimes complex design of the child restraint system and/or the sometimes poor quality of the users instructions, but also due to interface problems between a child restraint system and a passenger car. The car rear bench, the nowadays standard available seat belts and the lower belt anchorage locations are not designed to accommodate child restraint systems. One specific problem in this respect is the fact that child restraint systems, approved according to ECE Regulation 44, are tested using a simulated car bench with symmetrical bett anchorage locations, while rear outboard seating positions in passenger cars often have asymmetrical belf anchorage locations. These different anchorage locations will influence the crash performance of the child restraint system in real accidents and will probably lead to a less optimal effectiveness of the system.

In an attempt to address this issue, the TN0 Crash-Safety Research Centre started a literature survey and an experimental research programme. The performance of a forward facing child restraint system with a harness belt in standard ECE-R.44 dynamic sled tests has been compared with the performance in sled tests using a real car rear bench with symmetrical, as well as asymmetrical lower belt anchorage locations. Several test parameters have been varied and their influence has been analyzed in terms of dummy head displacement and head accelerations and chest accelerations. The effect of the bett anchorage location on the restraint effectiveness (Ride-Down-Effect) of the child restraint system has been studied.

A summary of the literature survey will be presented. Among other results, it will be shown that the dummy head displacement, in this most frequently used child restraint system, is increased by 50 percent if asymmetrical belt anchorage locations are used rather than symmetrical locations. This makes head contact with the car interior very likely in a real car crash. Therefore it is recommended, that regulations with respect to child restraint system are compatible with regulations concerning car seats and belts.

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