Rear Seat Occupant Safety: Kinematics and Injury of PMHS Restrained by a Standard 3-Point Belt in Frontal Crashes

Very little experimental research has focused on the kinematics, dynamics, and injuries of rear-seated occupants. This study seeks to develop a baseline response for rear-seated post mortem human surrogates (PMHS) in frontal crashes. Three PMHS sled tests were performed in a sled buck designed to represent the interior rear-seat compartment of a contemporary midsized sedan. All occupants were positioned in the right-rear passenger seat and subjected to simulated frontal crashes with an impact speed of 48 km/h. The subjects were restrained by a standard, rear seat, 3-point seat belt. The response of each subject was evaluated in terms of whole-body kinematics, dynamics, and injury. All the PMHS experienced excessive forward translation of the pelvis resulting in a backward rotation of the torso at the time of maximum forward excursion. The three subjects experienced maximum normalized chest deflections of 30%, 45%, and 30%, respectively, and maximum 3 ms clip resultant chest accelerations of 50, 42, and 52 g, respectively. Additionally, each PMHS received at least 13 rib fractures (maximum of 29 fractures), and flexion-tension induced neck injuries initiating in the lower cervical spine (C4-T1). The neck trauma ranged from ligament damage (AIS 1) to complete cervical spine transection (AIS 5).