Lap belt-induced Iliac Wing Fracture Risk Curve Development for Female PMHS in Frontal Sled Tests

This study estimates the tolerance of the female pelvis iliac wing under lap belt loading in frontal impacts. With future autonomous vehicles relying on seatbelts as the primary restraint, understanding pelvic injury biomechanics is crucial. The goal was to investigate pelvis fracture patterns resulting from seat belt loading among female specimens in MCW series and develop injury risk curves (IRCs) for iliac bone fracture.

Twenty-seven postmortem human subject (PMHS) frontal sled tests were conducted using a spring-controlled seat system. Tests included small and obese female surrogates at delta V levels of 32 kph and 50 kph, with variations in seatback recline angles, seat stiffness, and the presence of knee bolsters. Pelvic injury outcomes were analyzed, and IRCs were developed based on lap belt force, considering age, body mass index (BMI), and hip bone mineral density (BMD) as covariates.

The test produced iliac wing fracture coincided with the real-world report pattern in frontal collision. Two sets of IRCs were developed: Cohort A (small females) and Cohort B (all females). At 50% probability level, lap belt forces of 5.55 kN and 6.24 kN for cohort A and B, respectively. Age, BMI, and hip BMD significantly influenced fracture risk independently, but only for Cohort B.

The developed IRCs reflect the characteristics of the tested female specimens from the current dataset. The findings indicate that increased age and declining hip BMD are associated with elevated injury risk, whereas a higher BMI may confer a protective effect.