Design Implications for Improving an Anthropomorphic Test Device based on Human Body Simulations

To evaluate new restraint systems more advanced test tools are required. To guide the design of an Anthropomorphic Test Device (ATD) torso, simulations were performed with the LS-DYNA and RADIOSS codes using two human body models: an improved Total HUman Model for Safety (THUMS) version 3.0 and the HUMOS2LAB model. The baseline models were modified by removing a selection of internal organs, changing tissue stiffness and density, and/or blocking spinal joints to resemble ATD-like simplifications. Experimental setups with loading to the chest from an impactor, belts and airbag were simulated and the rib strains, mid sternal deflection and differential deflections from other assessment points on the rib cage, and thoracic effective stiffness were compared. Changing the material properties of intercostal muscles, ribs and sternum had the greatest influence on the differential deflections. Removing internal organs resulted in a global stiffness decrease of the thorax. However, it does not change the main features of the rib strain profile. If the lack of internal organs is compensated in an ATD by using stiffer rib materials, the differential deflections will decrease. There is a compromise between stiffness and mass representation in order to measure biofidelic differential chest deflections.