Evaluation of ISO CRS Envelopes Relative to U.S. Vehicles and Child Restraint Systems

Abstract

The objectives of this study are to use computer simulation to evaluate the ISO 13216-3:2006(E) child restraint system (CRS) envelopes relative to rear seat compartments from vehicles and CRSs in the U.S. market, and to demonstrate whether necessary modifications can be made to introduce such a system into compatibility evaluations between U.S. vehicles and CRSs. Three-dimensional geometry models for 26 vehicles and 16 convertible CRS designs developed previously were used. Geometry models of three forward-facing and three rear-facing CRS envelopes provided by the International Organization for Standardization (ISO) were built in the current study. The virtual fit process closely followed the physical procedures described in the ISO standards. The results showed that the current ISO rear-facing envelopes can provide reasonable classifications for CRSs and vehicles, but the forward-facing envelopes do not represent products currently in the U.S. market. In particular, all of the selected vehicles can accommodate the largest forward-facing CRS envelope, while half of the selected CRSs cannot fit within any forward-facing CRS envelopes. The results also indicate that the rear seat compartment in U.S. vehicles often cannot accommodate a large portion of convertible CRSs in the rear-facing position. The increased demand for vehicle fuel economy and the recommendation to keep children rear-facing longer may lead to smaller cars and larger CRSs, which may increase the potential for fit problems.