Global-Local Modeling of Aircraft Occupant Safety Assessment during Ejection

ABSTRACT: The extreme ejection conditions in the fifth-generation fighter F-35 could lead to occupant injury. Rocket sled testing of ejection seat with manikins is limited in simulating human response. The current neck injury models and injury criteria from automotive safety are inadequate for the ejection-related injury. We propose to develop the global-to-local finite element models (FEM) and simulation environment to enable fast, accurate simulation of occupant ejection, injury estimation and safety assessment. A fast-running global FEM is performed to establish the biodynamics of restrained occupant under ejection and windblast loadings and to identify critical areas i.e. cervical spine. The local FEM analyzes the spinal injury biomechanics, in which the global FEM provides appropriate boundary conditions. In Phase I we will design the simulation framework for occupants with different sizes in the ejection seat. The biodynamic response of global FEM will be validated against test and simulation data (ATB, Easy5). The detailed FEM of cervical-thoracic-lumbar-pelvis complex will be used to identify the critical variables in the ejection seat that contribute to soft tissue injury and vertebral fracture. A GUI framework will be established to facilitate modeling and simulations of occupant ejection. In Phase II, the FE models and GUI will be improved.; BENEFIT: The developed global-local FE modeling and the simulation environment will provide a new analysis tool for evaluation of ejection-related injury and safety improvement of ejection seat. The main benefit to the pilot is the faster development of better protection with improved survivability in ejection event. The models and software will be available to DoD and DoD prime contractors in open source format. The model development has great applicability to other DoD agencies in the field of ejection safety system. In Phase III, CFDRC plans to work with DOD and private manufacturers to help analyze and improve their ejection seat designs.