Impact test and numerical simulation of typical sub-cargo fuselage section of civil aircraft

This paper deals with impact test and numerical investigations on the crashworthiness of the typical sub-cargo fuselage section of a civil aircraft. The sub-cargo fuselage section with three-frame and two-span is designed and manufactured, and the 3.95 m/s impact test is conducted to research the failure modes and impact response characteristics for the upside-down sub-cargo fuselage section. The impact process is simulated by using the LS-DYNA finite element code. The impact velocity, displacement, and acceleration response are compared, and a good agreement between test results and numerical simulation results is observed. The energy absorption characteristics and impact load transfer path are further studied based on the verified finite element model (FEM). The results show that the impact phases are characterized by the bending and twisting of fuselage frames, the bending of middle stanchions and C-channel stanchions, the pull-off failure and shear failure of rivets, and the two plastic hinges formed at the joints of C-channel stanchions and fuselage frames. The fuselage frames and middle stanchions are the main energy absorption components. The impact load is transmitted along with the fuselage frames, middle stanchions, and C-channel stanchions to the cargo cross beams, and the area of middle stanchions is the most important energy absorption design area.