A comparative study of civil aircraft crashworthiness with different ground conditions

Civil aircraft crashworthiness performance related with emergency landing is one of the most important design factors according to the aviation regulations, and it is a highly nonlinear transient dynamic problem. Rigid floor and water are the typical ground conditions, and a significant amount of aircraft crashworthiness confirmed that impact response onto water is very different from that of rigid floor. The crashworthiness of two ground conditions is compared in this paper. Finite element model of typical civil aircraft is built, and physical property including mass and inertia are kept consistent with geometry model. Rigid blocks are used to simulate the structure above the cabin floor, the mass of passenger and the seat. Vertical drop test subject to the velocity of 7m/s is adopted. Result shows that concentrated and distributed loads are respectively applied on the bottom fuselage structure for rigid floor and water. The impact behavior with water is better than that with rigid floor. Fuselage frame are the most important component, and bottom structure and strut also would dissipate part of impact kinetic energy. As expected, the fuselage skin play an important role in the energy absorbing process during water impact, while it just dissipates a little part of impact kinetic energy for rigid floor condition.