Female and Combined Male–Female Injury Risk Functions for the Anterior Pelvis Under Frontal Lap Belt Loading Conditions

Abstract

Purpose

Iliac wing fractures due to lap belt loading have been observed in laboratory settings for 50 years and recent data suggest they are also occurring in the field. Automated driving systems (ADS) and other occupant compartment advancements are expected to offer enhanced flexibility in seating orientation, which could place a greater reliance on the seatbelt to restrain occupants. Such changes may increase seatbelt loads and create new challenges in successfully restraining occupants and mitigating injury to areas, such as the pelvis. Injury criteria exist for component-level male iliac wing fractures resulting from frontal lap belt loading, but not for females.

Methods

This study explored female iliac wing fracture tolerance in the same loading environment as a previous study that explored the fracture tolerance of isolated male iliac wings. Male and female fracture data were combined to evaluate the effect of sex. Injury risk functions were created by fitting Weibull survival models to data that integrated censored and exact failure observations.

Results

Twenty female iliac wings were tested; fourteen of them sustained fracture with known failure forces (exact), but the remaining six wings either (1) did not fracture or (2) fractured after an event that changed the boundary conditions (right-censored). The fracture tolerance of the tested specimens ranged widely (1134–8759 N) and averaged 4240 N (SD 2516 N).

Conclusion

Female data and combined male–female data were analyzed. Age was the only covariate investigated in this study that had a statistically significant effect and improved the predictive performance of the models.