Optimal Identification of Lumped Parameters in a Biodynamic Model of a Seated Occupant Subjected to Vertical Crash Loads in a Helicopter

A nonlinear biodynamic lumped parameter model was developed for a 50th percentile male occupant seated in an adaptive helicopter seat suspension subjected to vertical shock loads. The biodynamic model has four degrees-offreedom connected by nonlinear springs and dampers. The parameters were identified using occupant responses obtained from full-scale crash test data from the Sikorsky Advanced Composite Airframe Program (ACAP). The biodynamic model was experimentally validated by comparing two different 50th percentile male dummy responses obtained from vertical impact testing of a crashworthy composite fuselage section to the simulated responses. The biodynamic model was then used to develop optimal control techniques for an adaptive magnetorheological seat suspension. Significant reductions in lumbar loads were observed when compared to the experimental measurements where no adaptive seat suspension was employed.