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

TL;DR

This study develops injury risk functions for female and combined male-female iliac wing fractures under frontal lap belt loading, addressing a gap in injury criteria for females and considering the impact of sex and age.

Contribution

It provides the first injury risk functions for female iliac wing fractures and compares them with male data, incorporating censored data and age as a covariate.

Findings

Female fracture tolerance ranged from 1134 to 8759 N.

Age significantly affected injury risk predictions.

Combined male-female models improved injury risk estimation.

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.