Bridging the Gap: Development of frontal crash mode ATD Analogous human body models

Anthropomorphic variation is an important factor in computational studies using Human Body Models (HBMs), particularly regarding how such differences can influence observed kinematics and loading. Currently, a gap exists between Anthropomorphic Test Devices (ATDs) and human body models (HBMs). By necessity, there are differences in constitutive behaviors at a material level, however segment mass distribution and anthropometry differences can make matched simulations of ATDs and HBMs difficult to interpret, which has real-world implications for current or future regulatory applications. In response to this gap, we present Global Human Body Model Consortium (GHBMC) 50th percentile male models (M50-OS) analogous to Hybrid III and THOR 50th percentile male models to serve as intermediaries between the HBMs and ATDs in computational biomechanics studies. Statistical human shape models were sized to each ATD, individually, using measurement metrics from ANSUR I. The M50-OS model surface and body shape surface were then converted to both polygon data (STL) and nodal coordinates. Landmark registration was performed, and the morphed nodes were imported back into the existing M50-OS models to generate two morphed versions analogous to the ATDs. The qualification suites were obtained from each respective ATD manual and run against the baseline and morphed models. The models were also simulated in a frontal NCAP crash pulses (56 km/hr) to assess variation in loading in a regulatory crash environment. 33 simulations were run between all models. The LSTC Hybrid III version 151,214 (open access software, ANSYS, Canonsburg, PA), Adult Shape Parametric Model (open access model, UMTRI, Ann Arbor, MI), GHBMC M50-OS (Elemance, LLC, Winston-Salem, NC), Thor v2.7 (University of Virginia School of Engineering and Applied Science/NHTSA) were used in this study. All simulations were run using LS-Dyna R. 9.3.1 (ANSYS) on an in-house computational cluster. The Male 50th Percentile THOR Analogous Occupant Simplified (M50 THAN-OS) has 364 × 10³ elements and weighs 77.1 kg, the Hybrid III Analogous Occupant Simplified (M50 HAN-OS) has 370 × 10³ elements and weighs 79.2 kg. The M50 HAN-OS and M50 THAN-OS response data exhibited a closer match to their respective models overall when compared to the baseline M50-OS human. In the vehicle test environment, the airbag and seatbelt peaks between M50 HAN-OS and M50 Hybrid III at nearly the same time. The results indicate that the ATD analogous models exhibit more similar response characteristics to their ATD counterparts after correcting for shape and mass distribution discrepancies. The ATD analogous models therefore represent a novel means to compare anticipated biomechanical loading on an occupant under similar testing conditions that use ATDs. Furthermore, the models represent a potential bridge towards testing modes of interest that ATDs are not well suited or are not validated for, such as low speed maneuvering, or oblique and far-side modes of crash.