Influence of Impact Configuration on Rear Compartment Intrusion and Structural Countermeasures

Rear seat survival space intrusion pattern during severe rear-impact collisions is strongly influenced by the impact configuration. The relative contributions of rear seat pan forward intrusion versus rear seatback intrusion vary depending on the nature of the collision. In underride impacts, the rear wheels are pushed forward into the occupant survival space from below, causing the rear seat pan to move forward and upward relative to the vehicle interior. Conversely, override impacts tend to produce direct seatback intrusion into the rear compartment. This study employed a validated finite element model of a production vehicle, obtained from the NHTSA website, to simulate various types of rear compartment intrusions under different impact configurations. The analysis also evaluated structural countermeasures aimed at reducing occupant survival space intrusion. The results demonstrate that underride impacts primarily drive the forward motion of the rear wheels into the structure, establishing load paths that lead to structural failures and forward propulsion of the seat pan, in contrast to the seatback-dominant intrusion observed in override impacts. Furthermore, the study shows that structural reinforcements located at, above, and below the beltline are effective in mitigating survival space intrusion across different rear-impact scenarios.