Abstract: Based on finite element method and multi-body system dynamics theory, the dynamic response of depressed center flat car multi-body system, the fatigue life and elastic vibration of its depressed center flat underframe are studied. After the wheel-rail contact, track spectrum and vehicle nonlinear factors being calculated and simulated, the dynamic equations of depressed center flat underframe are established by using super-element method based on finite element analysis software ANSYS. The finite element analysis results are introduced into the dynamics software SIMPACK, and the multi-rigid-body system and rigid-flexible coupling system dynamics models of the depressed center flat car are established. Simulation calculation is carried out, then compared with the test result to study the effects of running speed and suspension parameter on the dynamic response of vehicle system. The dynamic clearance and fatigue strength of depressed center flat underframe are also analyzed. The results show that the rigid-flexible coupling model is more reasonable. The running speed of the loaded car should not be too high, and suspension parameters should be properly matched.

Key words: Depressed center flat car, Dynamic response, Fatigue life, Finite element analysis, Rigid-flexible coupling multi-body system