Investigation on the influence factors of lumbar-pelvic injuries for fifth percentile female occupants in frontal collision scenarios

Small-sized females are at an elevated risk of injury in traffic accidents, making it critical to investigate the external factors influencing the lumbar spine-pelvis injury risk in intelligent cockpits. This study explores the effects of collision conditions, seatback angle (defined as the angle of the seatback relative to the vertical), and the time-to-fire (TTF) of the anti-submarining airbag on lumbar spine-pelvis injury parameters using the TUST IBMs F05 model. A multiple linear regression analysis was performed to quantify the contribution of each factor to the injury parameters. The results indicate that collision conditions exert the most significant influence on injury parameters, with an impact proportion exceeding 70%. Lumbar spine injuries are more prevalent in the small overlap barrier impact (SOB). Among single factors, seating posture angles primarily affect the upper lumbar spine (L1–L2), where increased seating angles exacerbate the lumbar spine-pelvis injury risk. The lower lumbar spine (L3–L5) and pelvis are more sensitive to TTF, with delayed TTF reducing the lumbar spine-pelvis injury risk, particularly under frontal 50% overlap mobile progressive deformable barrier (MPDB) and SOB conditions. In conclusion, vehicle lateral acceleration and rotational loads are associated with an increased risk of lumbar spine-pelvis injuries. Reclined occupants are more vulnerable to such injuries. Conversely, delaying TTF can mitigate the lumbar spine-pelvis injury risk in occupants. These findings provide a theoretical basis for strategies aimed at reducing lumbar spine-pelvis injury risks for small-sized females in intelligent cockpits.