Simulation analysis of human neck injury risk under high-level landing impact

Abstract

When a spacecraft lands on the earth by parachute, the crewmen will be subjected to a high-level landing impact which could cause their body injuries in case of emergency. The purpose of this investigation was to analyse the human neck injury risk under the high-level landing impact, and to provide useful information for the protection design of the human-seat system in the spacecraft. On the basis of impact test, a mechanical model of the human-seat system was developed, and the acceleration responses at the seat and cushion were simulated using the finite element method. After the model was calibrated and validated, the forces and moments in the human neck were calculated. The degree of the human neck injury can be judged according to the standard of the human neck injury index (N ij < 1). The results showed that when both horizontal and vertical dropping velocity reach 7.5 m/s, the compressive force and extension moment in the human neck were, respectively, 6.58 kN and 100 Nm; and the injury index of the human neck was 1.81 (more than the critical value 1). It is concluded that under the high-level landing impact, the first reason for cervical fracture is the compressive force, and the second is the extension moment. It is necessary to take measures to reduce them to levels less than tolerance limits.