EVALUATING THE THORACIC RESPONSE IN A HUMAN BODY MODEL, COMPARED TO CADAVER EXPERIMENTS

Other conference contribution, 2011

Fatalities caused by car accidents accounted for 1.2 million worldwide in 2004. Chest injuries are the second death cause, after head injuries, in vehicle accidents. Devices to predict risk of injury are fundamental to develop and evaluate restraint systems that can mitigate the injury severity and reduce the fatalities. This can be achieved with mathematical Human Body Models (HBM). An HBM needs to be biofidelic, both in terms of size and biomechanical response. Herein, the biofidelity of the thorax region in an HBM is evaluated. The evaluation focuses on whole body kinematics and chest response during frontal car accidents. Finite element simulations with an HBM were performed with the code LS-DYNA [1]. A modified version of Total HUman Model for Safety v3.0 (THUMS) [2] has been the basis for the work presented here. THUMS was modified to improve its robustness and numerical stability. The meshes of the rib cage, skin around the ribcage, and intercostal muscles were refined. THUMS represents a 50th percentile male and has approximately 150,000 elements. It was compared with cadaver pendulum impacts [3], table top tests [4], and sled tests [5]. The pendulum test consist of a cylinder with diameter 125 mm, mass of 23.4 kg and an initial speed of 4.3 m/s impacting on the middle of the sternum. The table top tests included four loading conditions of the chest: hub, diagonal belt, double diagonal belt, and distributed load. The sled test was performed at 40 km/h, using a three point standard seat belt. The model has been compared to cadaver experiments on different load cases, which are representative of modern automotive restraint systems. In general, THUMS showed a good agreement with the experimental corridors for the pendulum and table top tests. The chest response in the sled test differed for the lower chest, possibly due to the absence of biofidelic fracture simulations in the THUMS. After comparing the kinematic and dynamic responses of THUMS with cadaver experiments it was concluded that the model is adequate to simulate the human response under frontal impacts. The next step is to identify parameters that can predict the risk of rib fracture and then become a tool to evaluate new restraint systems.