Using anthropometry-based scaling to predict responses across sex in reclined frontal impact sled tests

Field data studies have suggested greater injury risk in motor vehicle crashes for females compared to males. Data on female responses may provide more insight into these sex-based differences in injury risk, but few sled tests have been conducted with female subjects, with most cases being of either small or obese anthropometries. Since numerous sled tests have been conducted using mid-size male post mortem human subjects, anthropometry-based scaling of mid-size male responses is a potential approach to leverage this mid-size male data for a broader range of applicability. This study aimed to determine if scaling to predict female responses from male responses is suitable for a reclined condition and evaluate the effectiveness of varying anthropometry-based scaling techniques in predicting female responses from male responses.

Data from frontal impact sled tests conducted on four mid-size male and three mid-size female post mortem human subjects in a reclined posture were used. Geometric scaling using dimensional analysis (equal stress-equal velocity approach) was then implemented on the male data to test the effect various scale factors had on predicting female response. These scaling factors were based on mass, stature, torso height, torso volume, and torso volume at torso height.

Predictions results varied, with lap belt force and forward excursions of bony landmarks yielding high overall prediction scores and vertical excursions of bony landmarks yielding lower overall prediction scores. Generally, the unscaled responses also yielded high prediction scores, and while scaling offered an improvement to the overall prediction score, this suggested that anthropometry-based differences may not fully explain male-female differences in reclined occupant response. Torso volume yielded the highest overall prediction score for the greatest number of responses, but the anthropometry measure that yielded the highest average overall prediction score across all responses varied.

Marginal differences in the predictive capabilities of the different anthropometry-based measures were found, but, in general, anthropometry was not able to fully explain differences in the responses observed between sex. Overall, this study highlighted the need for further whole body sled tests with mid-size female PMHS to further investigate male-female differences in occupant kinematics.