Global Sensitivity Analysis for Vehicle–Track Interactions: Special Attention on Track Irregularities

The dynamic vehicle–track interactions are complex processes due to the highly nonlinear terms and spatially varying excitations in vehicle design, track maintenance, dynamic prediction, etc. Therefore, it is of importance to clarify the key factors affecting the dynamic behaviors of system components. In this paper, a comprehensive model is presented, which is capable of analyzing the global sensitivity of vehicle–track interactions. In this model, the vehicle–track interactions considering the nonlinear wheel–rail contact geometries are depicted in three-dimensional (3D) space, and then the approaches for global sensitivity analysis (GSA) and time–frequency analysis are combined with the dynamic model. In comparison to the local sensitivity analysis, the proposed model has accounted for the coupling contributions of various factors. Thus, it is far more accurate and reliable to evaluate the critical factors dominating the vehicle–track interactions. Based on the methods developed in the present study, numerical examples have been conducted to draw the following marks: track irregularities possess the dominant role in guiding the dynamic performance of vehicle–track systems, besides, the vertical stiffness of primary suspension and rail pads also shows significant influence on vertical acceleration of the car body and the wheel–rail vertical force, respectively. Finally, a method is developed to precisely extract the characteristic wavelengths and amplitude limits of track irregularities.