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The role of seatback strength on occupant motion during rear-end collisions has been a focus of scientific investigation for decades. Despite being an integral component of the occupant restraint system, the role of seat belt restraints and the potential effect of various seat belt restraint system components, like pretensioners and latch plate design, on occupant motion and injury potential during rear-end collisions has received less attention. This study identifies and highlights what is currently understood about the role of seat belt restraints and components in rear-end collisions from the existing literature in detail for the first time. Previous studies that have investigated the role of pretensioning in occupant motion and loading did not provide detailed assessments of pretensioning effects on webbing loads and displacement, nor did they discuss the relationship between pretensioner deployment and latch plate design.

This paper investigates the role that load-limiters play with respect to the performance of occupant protection systems, with focus on performance in frontal crashes. Modern occupant protection systems consist of not just the seat belt, but also airbags, interior vehicle surfaces and vehicle structure. Modern seat belts very often incorporate load-limiters as well as pretensioners. Published research has established that load-limiters and pretensioners increase the effectiveness of occupant protection systems. Some have argued that load-limiters with higher deployment thresholds are always better than load-limiters with lower deployment thresholds. Through testing, modeling and analysis, we have investigated this hypothesis, and in this paper we present test and modeling data as well as a discussion to this data and engineering mechanics to explain why this hypothesis is incorrect.

The performance of two types of forward facing child restraint systems (CRSs), belt-positioning boosters (BPBs) and CRSs with an integral 5-point harness were compared in frontal and side-impact testing. Performance criteria in frontal impacts (head injury criteria (HIC), chest acceleration, head excursion and knee excursion) was evaluated by comparing a large set of NHTSA-run FMVSS 213 compliance test data generated with the 3-year-old-sized anthropomorphic dummy (ATD). Side-impact performance was evaluated by conducting a series of sled tests and comparing the relative head excursion of a 3-year-old-sized ATD. FMVSS 213 compliance test data shows that the average HIC, chest acceleration, and head and knee excursions are comparable for BPBs and harness CRSs. ATDs in BPBs experienced a slightly higher average HIC, and a slightly lower average head excursion than ATDs in harness CRSs without a tether.

This study investigates the technique used and forces applied on the latch plate and buckle during typical seat belt operation and driving conditions. These techniques and forces are relevant to whether the latch plate can be partially engaged with the buckle during typical operation and whether the latch plate will dislodge during vehicle operation. In addition to studying the insertion of the latch plate, we examined the tensile forces that are applied to the latch plate and buckle during typical, non-crash driving conditions, and how these forces compare to the performance requirements established by the National Highway Traffic Safety Administration (NHTSA) as part of Federal Motor Vehicle Safety Standards (FMVSS) 209. These tensile forces are important in understanding whether the latch plate is likely to dislodge from the buckle if it is in a position of partial engagement.