Sensitivity analysis and optimization of nonlinear vibration of cargo wagon model

In this paper the vertical vibration of a railway vehicle model due to harmonic irregular rail track is presented. Two degree of freedom nonlinear model of rail vehicle is used for this analysis. Nonlinear Hertzian contact theory is applied for wheel/rail contact modeling. Nonlinear equations of motion of the system are solved using method of multiple scales (MMS). To validate the analytical method used in this article, the results from this method are compared with the results obtained from the Runge-Kutta numerical solution. To determine the sensitivity of normal contact force between wheel and rail to the cargo wagon parameters, the sensitivity analysis has been done using local and relative methods. The vehicle driving comfort has become one of the important factors of vehicle quality and received increasing attention. In order to achieve this, the genetic algorithm is applied to search for the optimal parameters of the vehicle suspension in order to minimize wagon vertical displacement to achieve the best comfort of the drivers. Obtained results from the optimization demonstrate a considerable improvement of its dynamic response as a result of reduced accelerations.