| Along with the development of railway enterprise and the fierce competition of traffic transportation market, the speed of train increased day by day. The crash accident of train brought great damage to the lives and properties. So the passive safety of high-speed passenger vehicle was highly considered. Because the physical destructive testing was very expensive, most of the researches used the method of simulation. As the development of explicit finite element method and the emergence of high performance hardware and software of computer, numerical simulation was possible for high-speed crash. The dissertation studied the crash characteristics of high-speed crash with large deformation, optimized the energy absorption characteristic of the draught beam. These studies were very practical and useful for improving the passive safety of high-speed passenger vehicle.The main contents and achievements of this dissertation were listed below:1.Theory for crash simulationIn order to simulate the crash of high-speed passenger vehicle, this paper expatiated the basic impact simulation control equations of explicit finite element method. In particular the following concerns were investigated: integral format, critical time step, nonlinear performance of material and geometry, contact-impact interface algorithm, calculation of frictional force, hourglass control, treating of rigid wall, which were the bases for numerical crash simulation.2. FE model of passenger vehicleAccording to the design drawing, the three-dimensional model was set up using the software of UG. After the mid-surface was taken out from the three-dimensional model, the model only with mid-surface was input to the software of PAM/CRASH. Taking into account of the characteristic of crash deformation and the quality of element, the model was meshed with shell element. The whole FE model was set up through selecting material model and defining the boundary condition, the number of elements for single vehicle was up to 268,119. Some hybrid III dummies were put into vehicle at random.3.Crash simulation of railway passenger vehicle(1) Three cases of crash for single vehicle were studied: the frontal crash on single vehicle with fixed rigid-wall, with movable rigid-wall, and with movable barrier. The simulation data indicated: crash time was very short; very large plastic deformation was produced in the head of vehicle body, and very little deformation was produced in the middle and the tail; the kinetic energy was mainly absorbed by a few structures; the crash acceleration got max value at the crash location, and it got small from the front to the end of the vehicle; as the mass of rigid-wall was more big, the change velocity of vehicle was more great, the deformation of vehicle was more large.(2) This paper also simulated the frontal crash on two vehicles with fixed rigid-wall and one vehicle with another vehicle. Because of the difference of stiffness of the up and the low parts of the end of the vehicle, one vehicle might creep up another vehicle. The simulation of slanting crash of threevehicles with fixed rigid-wall was studied also, and the derailment might happen.(3) By contrast to the crash of car, the characteristics of the vehicle crash simulation were the large size of model and the long time of simulation calculation. It took 7.3h to simulate the process of the frontal crash of two vehicles with another two vehicles using parallel technology, so the parallel calculation was very important for the crash problem.4. Structural optimization of characteristic of crash energy absorptionDraught beam was the primary energy absorption structure in vehicle crash, so the dimensions of draught beam determined the performance of vehicle crash. Using the method of response surface, dimensions of draught beam as the design variables, and the crushing axial force as constraint, dynamic structural optimization was performed to maximize the crushing energy absorption of draught beam. The results demonstrated the response surface method was feasible, improved computing e... |
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