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Recent field data have shown that the occupant protection in vehicle rear seats failed to keep pace with advances in the front seats likely due to the lack of advanced safety technologies. The objective of this study was to optimize advanced restraint systems for protecting rear seat occupants with a range of body sizes under different frontal crash pulses. Three series of sled tests (baseline tests, advanced restraint trial tests, and final tests), MADYMO model validations against a subset of the sled tests, and design optimizations using the validated models were conducted to investigate rear seat occupant protection with 4 Anthropomorphic Test Devices (ATDs) and 2 crash pulses.

Injuries of the Occipitoatlantoaxial (Occ-C2) region (also known as atlanto-occipital injuries) are the most common form of cervical injury in children aged ten years and younger. The crash studied in this paper is unique in that there were three children ages 3, 6 and 7 involved in a frontal crash with a delta V of 28mph with each child receiving a nonfatal Occ-C2 injury of varying degrees. The 3 and 6 year-old children were remarkably similar in height and weight to the 3 and 6 year-old Hybrid III ATD's. Also, unique to this case is the fact that the right rear 6 year-old occupant likely sustained an Occ-C2 injury prior to impact with the frame of the front passenger seat. This crash environment was recreated utilizing MADYMO occupant simulation software. The models for the Hybrid III 3 and 6 year-old ATDs were used to represent the occupants in this crash.

An inflatable restraint tailoring method has been developed which shows the effect of the passenger air bag module characteristics on occupant performance in the unbelted condition. The tailoring algorithm uses PASSIM-PLUS1 to predict dummy injury measures and kinematics. From these measures, restraint efficiency is evaluated from peak chest deceleration and relative displacement. This efficiency is them used to evaluate the occupant sensitivity to air bag characteristics and to design the module. The tailoring method evaluates a specified range of inflator outputs and bag sizes via the PASSIM-PLUS model. The venting is adjusted for each air bag module configuration to produce a constant bag penetration by the occupant. The results of these model runs are used to establish trends for passenger air bag module design based on a specific vehicle environment and crash pulse.

In this study, two sled series were conducted with a sled buck representing a compact vehicle. The first series of tests focused on the effects of crash pulse, impact angle, occupant size, and front seat location on rear seat occupant restraint with a generic rear-seat belt system without pre-tensioner or load limiter. The second series of tests focused on investigating the benefit of using advanced features for rear-seat occupant restraint in the most severe crash condition in the first sled series. The first series of tests include 16 test conditions with two impact angles (0° and 15°), two sled pulse (soft and severe), and four ATD sizes (HIII 6YO, HIII 5th female, HIII 95th male, and THOR-NT) with two ATDs in each test. The driver seat was located at the mid position, while the front passenger seat was positioned such that a constant distance between the ATD knee and the front seat is achieved.

A driver airbag module has been developed with single stage inflator in an attempt to determine the 05th% ATD measured dummy injury response (“MDIR”) in out-of-position scenarios (two NHTSA positions). Through computer simulations, dynamic MDIRs for in-position 05th%ile and 50th%ile dummies were evaluated as well. It typically takes many design iterations to finalize a driver side module configuration to meet FMVSS208 regulatory conditions. Some typical parameters are tear seam cover design, cushion folding pattern and inflator output. In this paper, a Taguchi design of experiments was used to evaluate the influence of module design parameters. A MDIR comparison between a proposed new driver airbag module with a single stage inflator and a baseline module with a dual stage inflator was made not only for out-of-position tests, but also in-position crash simulations.

Recent field data have shown that the occupant protection in vehicle rear seats failed to keep pace with advances in the front seats likely due to the lack of advanced safety technologies. The objective of this study was to optimize advanced restraint systems for protecting rear seat occupants with a range of body sizes under different frontal crash pulses. Three series of sled tests (baseline tests, advanced restraint trial tests, and final tests), MADYMO model validations against a subset of the sled tests, and design optimizations using the validated models were conducted to investigate rear seat occupant protection with 4 Anthropomorphic Test Devices (ATDs) and 2 crash pulses.