Analysis of the Effect of Seat Rotation on Occupant Chest Injury in Autonomous Vehicles during Crashes

This study analyzes the impact of rotational seat protection on occupant chest injuries during crashes in SAE Level 4 and Level 5 autonomous vehicles. All seat rotations discussed are specifically about rotation around the vehicle’s z-axis (vertical axis). Three models were established: a conventional seatbelt multirigid body, a new seatbelt multirigid body, and a THUMS (Total HUman Model for Safety) chest skeleton finite element model. Eight typical z-axis seat-rotation crash scenarios were examined. Four indicators, including occupant kinematic response, combined thoracic index, chest injury risk, and chest stress, assessed the chest injuries. The experiments indicated that z-axis rotational seat protection for conventional seats led to higher chest injuries for occupants in the seat-rotation crash conditions. The new type of seat with leg baffles and foot support was found to effectively improve the occupant’s chest safety in the precrash stage, that is, the seat-rotation stage, and the protection afforded was not limited by the rotation direction or -angle; this met the requirements for autonomous vehicles, and is of great significance for the improvement of autonomous vehicle precrash safety.