Sensitivity analysis of the critical speed in a railway bogie system with uncertain parameters

An extended Dichotomy method is proposed for an accurate determination of the critical speed of railway vehicles. The high-dimensional Hermite orthogonal polynomial (HOP) based on the independent and normal distribution parameters is derived. Both the Monte Carlo (MC) method based on a Latin hypercube sampling (LHS) and the HOP expansion method using different collocation methods are compared to investigate the statistical characteristics of the critical speed of a Chinese railway bogie. After that, the relation between the critical speed and the random input parameters is approximately constructed. The relation is then used to conduct a relative local sensitivity analysis (LSA), a global sensitivity analysis (GSA) and a regional sensitivity analysis (RSA) of the bogie. It is indicated that RSA is a good method for sensitivity analysis of the critical speed due to its good efficiency and trusty precision. The results also show that the secondary lateral damper is the most important parameter to the critical speed for this bogie. By increasing its values and reducing its variation range, the critical speed can be increased and the variation is decreased. It may offer some instructions and practical values for vehicle design, operation, and comprehensive evaluation of the stability of railway vehicles.