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A Two-Step Composite Time Integration Scheme for Vehicle-Track Interaction Analysis considering Contact Separation

The two-step composite time integration scheme is combined with the linear contact relation between the wheel and rail (termed the two-step method) to solve coupled vehicle-track dynamic problems. First, two coupled vehicle-track models with different degrees-of-freedom are constructed, in which a vehicle-track system is modeled as two subsystems and the interaction between the two subsystems is implemented via kinematic constraints. Then, the two-step method is applied in the models to simulate several cases, and the accuracy and efficiency of this method are discussed in comparison with additional methods of the Newmark family. Contact separation can also be simulated using the same scheme without causing spurious oscillations for large integration steps. The results indicate that track irregularities can cause wheels to momentarily lose contact with the track, causing large impacts between the wheels and rail. Additionally, with the increase of the running velocity, contact separation will occur more frequently. The adoption of the two-step integration method can ensure the accuracy of solutions and significantly increase the computational efficiency; moreover, the matrixes representing the model information will not change during the calculation process, so the substructure data exported from commercial finite element software can be directly adopted.