Evaluating submarining in female human body models: Predicting occurrence and timing through biomechanics and...

Submarining occurs during vehicle crash when the lap belt slips over the pelvis and loads the abdomen. Countering this motion is an interdisciplinary challenge, requiring expertise in biomechanics and restraint design to develop countermeasures and quantitative metrics to predict it. Most prior research into submarining has focused on the 50^th percentile male. This study compares small female models to reference sled tests and evaluates two methods of identifying submarining occurrence and timing in Human Body Models (HBMs).

A 5th percentile female model and age-adjusted 70-year-old 5th percentile female model (GHBMC) were simulated in sled environments based on Trosseille et al. Three seating configurations were run, two of which were designed to induce submarining. Submarining was assessed in the HBMs in two ways; analyzing the divergence between pelvis strain and belt force timing via CORA's phase score, and analyzing an internally derived metric based on abdominal organ strain energy density (SED) time history, which is independent of restraint system-based measures.

HBMs compared well to experimental corridors and time-history data (average CORA score of 0.73). Like the PMHS, neither model submarined in the low-speed case, while both submarined in the high-speed cases. The pelvic strain and belt force phase correlation scores were on average 0.998 (out of 1) in the non-submarining cases and 0.217 in the submarining cases. The peak SED values were on average 12 times greater in the submarining cases than non-submarining cases. The models tended to predict submarining earlier than the experiments.

This study illustrates that both restraint based and internally derived HBM metrics can be used to predict the occurrence and timing of submarining. It further addresses a gap in the literature to relate to female HBM validation in frontal impact conditions. The findings will enable engineers to more effectively utilize HBMs to contribute to the development of safer vehicles, linking biomechanics to restraint design.