Numerical Investigation of the Performance of Current Vehicle Rear Seats Using Finite Element Analysis

Experimentation and regulations involving vehicle occupant protection typically focus on the front seats. Therefore, the safety of the front seats has increased greatly over the years, usually outperforming the rear seats. The rise of ridesharing and automated driving systems (ADS) is expected to increase rear-seat occupancy by adults, which may increase occupant injury risks. The main objective of this study was to develop an efficient numerical methodology that could be used to evaluate the safety performance of current vehicle rear seats. The rear-seat models of eight vehicles were developed based on their geometry reconstructed from three-dimensional (3D) digitizer scans. Seat foam material properties were taken from tests of each seat. Validated Finite Element (FE) models of THOR-50M and Hybrid III male 50th percentile Anthropomorphic Test Devices (ATDs) were positioned and settled in each seat model. The frontal New Car Assessment Program (NCAP) crash pulses were applied to each vehicle. Injury likelihood was assessed by a summary of the AIS3+ risk curves for the head, neck, and chest. Then, six rear seats were selected and tested on a sled. The restraint system model and dummy precrash position were slightly adjusted based on the test data. The accuracy of the numerical approach to investigate the safety of rear seats was evaluated under varying scaled NCAP pulses against sled test data. Overall, the seat models with advanced restraints (e.g., pretensioners, load limiters) and/or a steep seat pan angle had the lowest injury risk. The results of the simulations with varying impact pulses showed reasonable agreement with test data that validate the numerical assessment of rear-seat safety proposed in this study. The total injury risk ranged from 36% to near certainty, indicating a significant room for improvement in the design of rear seats.