(D-128) AN ANALYSIS OF AIRBAG DEPLOYMENT APPLIED TO AN OUT-OF-POSITION SEATED 50TH PERCENTILE MALE HUMAN BODY MODEL

Introduction:: In a vehicle crash, posture and position play a role in clinical outcome for the driver. Due to pre-crash maneuvering or multiple impacts, an occupant may be positioned closer to the point of deployment of an airbag. Previous research studies have reported on human body model thoracic loading, but no studies have explicitly validated the models’ response in a near airbag deployment scenario. We modeled this scenario using the Global Human Body Model Consortium (GHBMC) Male 50th Percentile Occupant (M50-O) to emulate testing done on Post Mortem Human Subjects (PMHS) in LeBarbe et al. 2005 (Figure 1).

Materials and Methods:: A steel plate was attached to the back of an airbag provided by Stellantis, and rigidly fixed in space. The model was then positioned so that the anterior-most point of the sternum was 52 mm from the airbag. The same test was repeated on the 70 year old aged version of M50-O presented in von Kleeck et al, 2022 [1]. The model and airbag matched the orientation found in the experimental testing, and gravity was applied to the simulation. Airbag to model contact force was measured and compared to the force transducer on the back of the steel plate. Force data from LS-Dyna was filtered to SAE J211 CFC 180 and plotted against the individual PMHS data (n = 4, mean age = 77.8 years). Fracture was assessed using strain data from the ribs and the Metriks fracture prediction tool (Metriks v. 0.6, Elemance, Winston-Salem, NC) which is based on a probabilistic method [2]. The simulation was run for 40 ms using LS-DYNA R10.2.0 on the WFU DEAC cluster.

Results, Conclusions, and Discussions:: RESULTS
Greater contact force was observed in the simulations than the experimental data. Yet, the model underreported rib fracture, with zero in the M50-O and one in the M50-O+aged 70 YO, compared to the PMHS with an average of 4. Using the parameters outlined in the paper, the airbag exhibited a normal deployment and response under load.
CONCLUSIONS
The contact force and the model kinematics appeared to be in line with the experiment. The average age of the PMHS was 78, whereas GHBMC M50-O is developed from a 29-year-old male but is considered age-undefined. While the aged model is closer in age to the PMHS, M50-O’s differences in cortical thickness and mineral density between model and PMHS, may contribute to the underreporting of rib fractures. Future efforts will focus on potential differences in the boundary conditions which may also contribute to the lack of observed rib fracture.

Acknowledgements (Optional): : This work was supported by the Global Human Body Models Consortium, LLC and NHTSA under GHBMC Project No. WFU-006. F. Scott Gayzik is a member of Elemance, LLC, which distributes academic and commercial licenses for the use of GHBMC-owned computational human body models.

References (Optional): : [1] B. W. von Kleeck, Z. Hostetler, K. Fleischmann, A. A. Weaver, and F. S. Gayzik, “Age targeted human body models indicate increased thoracic injury risk with aging,” Traffic Inj. Prev., vol. 23, no. sup1, pp. S74–S79, Oct. 2022, doi: 10.1080/15389588.2022.2097223.
[2] “Predicting Rib Fracture Risk With Whole-Body Finite Element Models: Development and Preliminary Evaluation of a Probabilistic Analytical Framework - PMC.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503420/ (accessed Feb. 15, 2023).