Riding comfort optimization of railway trains based on pseudo-excitation method and symplectic method

This research is intended to develop a FEM-based riding comfort optimization approach to the railway trains considering the coupling effect of vehicle–track system. To obtain its accurate dynamic response, the car body is modeled with finite elements, while the bogie frames and wheel-sets are idealized as rigid bodies. The differential equations of motion of the dynamic vehicle–track system are derived considering wheel–track interaction, in which the pseudo-excitation method and the symplectic mathematical method are effectively applied to simplify the calculation. Then, the min–max optimization approach is utilized to improve the train riding comfort with related parameters of the suspension structure adopted as design variables, in which 54 design points on the car floor are chosen as estimation locations. The K–S function is applied to fit the objective function to make it smooth, differentiable and have superior integrity. Analytical sensitivities of the K–S function are then derived to solve the optimization problem. Finally, the effectiveness of the proposed approach is demonstrated through numerical examples and some useful discussions are made.