1 Copyright © 2012 by ASME Proceedings of the ASME 2012 International Mechanical Engineering Congress & Exposition IMECE2012 November 9-15, 2012, Houston, Texas, USA IMECE2012-89067 AN ENHANCED ARTICULATED HUMAN BODY MODEL UNDER C4 BLAST LOADINGS X.G. Tan CFD Research Corp. Huntsville, AL R. Kannan CFD Research Corp. Huntsville, AL Andrzej J. Przekwas CFD Research Corp. Huntsville, AL. Kyle Ott Johns Hopkins Univ., Applied Physics Lab. Columbia, MD Tim Harrigan Johns Hopkins Univ. Applied Physics Lab. Columbia, MD Jack Roberts Johns Hopkins Univ. Applied Physics Lab. Columbia, MD Andrew Merkle Johns Hopkins Univ. Applied Physics Lab. Columbia, MD ABSTRACT Previously we had developed an articulated human body model to simulate the kinematic response to the external loadings, using CFDRC’s CoBi implicit multi-body solver. The anatomy-based human body model can accurately account for the surface loadings and surface interactions with the environment. A study is conducted to calibrate the joint properties (for instance, the joint rotational damping) of the articulated human body by comparing its response with those obtained from the PMHS test under moderate loading conditions. Additional adjustments in the input parameters also include the contact spring constants for joint stops at different joint locations. By comparing the computational results with the real scenarios, we fine tune these input parameters and further improve the accuracy of the articulated human body model. In order to simulate the effect of a C4 explosion on a human body in the open field, we employ a CFD model with a good resolution and the appropriate boundary treatment to obtain the blast loading condition on the human body surface more accurately. The numerical results of the blast simulation are shown to be comparable to the test data. With the interface to apply the blast pressure loading from the CFD simulation on the articulated human body surface, the articulated human body dynamics due to the C4 explosions are modeled and the simulation results are shown to be physiological reasonable. INTRODUCTION We have developed an articulated human body dynamics model in which the human body is represented accurately in both the geometry and the inertial properties ([6]). The model has been used to effectively acquire the kinematic response of human body under the blast wave loading. The simulation results provide the useful insight and boundary conditions for the detailed injury biomechanics modeling of susceptible body parts or joints. The developed implicit multi-body solver allows us to use a larger time step while enforcing the kinematic constraints well. In contrast, the explicit models (e.g., MADYMO model in [4]) are forced to employ small time steps for both accuracy and stability. In this work we have further validated the articulated human model with the test data on Post-Mortem Human Subject (PMHS). By comparing the acceleration and angular acceleration at the head center of gravity, we have found appropriate input parameters such as the spring and damping constants at the joint locations which lead to the physiological response of human kinematics. The accuracy of articulated human body dynamics also depends on how well we can capture the blast loading on the surface of object. Many researchers have used the ConWep to generate the blast loading ([3]). It is known that the ConWep does not give the accurate results for a complex geometry like a human body. Hence, we employed a CFD model to capture the blast loading condition for the human body subjected to the C4 explosion in the open field, via a novel and efficient sequential 1D and 3D approach. The numerical treatment of the external boundary is very challenging for the open field CFD simulations. In our approach we created a relative large computational domain to alleviate the artificial boundary effect. The numerical results of the blast simulation are shown to be comparable to the test data. After applying the blast pressure loading resulting from the CFD simulation on the human body surface, the articulated human body dynamics under the C4 explosions are simulated and analyzed.