ROLLING NOISE GENERATED BY RAILWAY WHEELS WITH VISCO-ELASTIC LAYERS

The noise-generating characteristics of two types of railway wheel design have been studied theoretically. These are “resilient wheels” in which a viscoelastic layer is located between the type and the web, and wheels with constrained layer damping treatments applied to the web. A method of predicting the rolling noise of these wheel types using the TWINS rolling noise model has been developed. For this, a modal description of the wheel must be constructed. A finite element model is used to calculate the mode shapes and modal masses. The modal damping is predicted by a complex modal analysis of the finite element model in which a material-specific damping parameter is used. Analyses have been carried out for a number of resilient wheels with different stiffnesses of their resilient layer, including the case where the wheel becomes a conventional one by specifying the resilient element as steel. The sound power radiated by both the wheel and the rail are shown to be dependent on this stiffness. A number of configurations of wheels with constrained layer damping treatments have been analysed taking into account the frequency variation of the properties of real damping materials. Significant reductions in the wheel sound power are shown to be possible.