Biodynamic Model of a Seated Occupant Exposed to Intense Impacts

Abstract

Quantitative comparison of biodynamic responses, simulated using the Patil or Liu lumped parameter models, were carried out with respect to experimental anthropomorphic test dummy response data obtained from the Sikorsky advanced composite airframe program helicopter crash test. The biodynamic responses obtained from these models were characterized by large offsets from the experimental peak magnitudes, large perturbations in biodynamic displacements, and delayed response. The inability to accurately predict biodynamic response using either model led to development of a new four-degree-of-freedom nonlinear biodynamic model corresponding to a Hybrid II 50th-percentile male occupant, the parameters of which were identified by minimizing the least-square error between the simulated and advanced composite airframe program experimental responses. The new model accurately predicts peak magnitude, overall shape, and duration of the biodynamic transient response, with minimal phase shift. The biodynamic model was further validated using data from the crashworthy composite fuselage drop experiment conducted by Fasanella and Jackson (“Impact Testing and Simulation of a Crashworthy Composite Fuselage Section with Energy-Absorbing Seats and Dummies,” Journal of the American Helicopter Society, Vol. 49, No. 2, 2004, pp. 140–148). The biodynamic model overpredicted the peak lumbar loads by 1.06% when compared to the pilot’s anthropomorphic test dummy response from the Sikorsky advanced composite airframe program experiment, and it predicted lumbar loads within when compared to crashworthy composite fuselage experiments.