Effects of Seatback Recline and Belt Restraint Type on PMHS Responses and Injuries in Rear-Facing Frontal Impacts

One potential nonstandard seating configuration for vehicles with automated driving systems (ADS) is a reclined seat that is rear facing in a frontal collision. However, there are very limited biomechanical data in the rear-facing seating configuration in high-speed frontal collisions. The objectives of this study are (1) To investigate biomechanical responses and injuries from postmortem human subjects (PMHS) seated in an original equipment manufacturer (OEM) seat with a fixed D-ring (FDR) in a rear-facing frontal impact with ΔV of 56 km/h and (2) To compare PMHS responses and injuries from the FDR condition to those from an all-belts-to-seat (ABTS) condition tested in a previous study. The seat was rigidized in the rearward direction using a reinforcing frame that contained instrumentation to measure occupant loads applied to the seats. PMHS kinematics were measured using accelerometers and angular rate sensors that were installed at various body regions. Strain gages were attached to both anterior and posterior aspects of the ribs, as well as the midshaft of the femora and tibiae. Chest deformations were quantified using a chestband that was installed at the mid-sternum level. Biomechanical responses from the FDR condition were compared to those from the ABTS condition. Seatback loads and ramp-up motions were higher in the FDR than in the ABTS. Therefore, more injuries were documented in the FDR condition than in the ABTS. The design of human body models (HBMs) and anthropomorphic test devices (ATDs) in rear-facing seating configurations during a high-speed frontal impact can be enhanced using the biomechanical responses and injuries provided in this study.