Research on dynamic stiffness match form of indirect fastener based on rail high-frequency wear characteristics

The stiffness combination of the dual-layer pads in indirect fastener systems significantly influences high-frequency wheel-rail wear behavior. However, the actual stiffness exhibits strong nonlinearity and non-uniformity due to the deformation of the steel plate and the frequency-dependent stiffness of the elastic pads, making it challenging to clarify the underlying mechanisms. To address this, this study develops a dynamic model for indirect fasteners by modeling the ironbase using an Euler beam and representing the frequency/load-dependent stiffness of the elastic pads using a Multi-Point Supported Fractional Derivative Poynting-Thomson (MS-FDPT) model. The study investigates the effects of pad stiffness and damping match form on rail wear. The results indicate that, considering the contact filtering effect, rail wear in the 0-1250 Hz range is primarily concentrated in four major resonance bands corresponding to P2 form, second- and third-order rail bending, and pinned-pinned resonance modes. Neither single-layer support models nor fastener stiffness models that only account for the mass participation of the ironbase can accurately reflect the actual in-service behavior of indirect fasteners, with a maximum simulation error of 136 Hz in the dominant rail acceleration frequency. Without altering the nodal stiffness of the fasteners, adopting a "hard-upper, soft-lower" stiffness match form effectively reduces resonance frequencies other than the P2 form and mitigates wear at these resonance frequencies. The damping characteristics of the fastener system are primarily determined by the lower-stiffness pad. The best suppression effect on high-frequency wheel-rail wear is achieved by increasing the damping of both pads simultaneously, whereas increasing the damping of only the high-stiffness pad may exacerbate high-frequency wear.