Research on dynamic characteristics of novel filled damping block mesh-type rail pads for heavy haul railways

Currently, the commonly used rail pads for heavy haul railways are grooved rubber rail pads (GRRP) and prismatic thermoplastic polyester elastomer (TPEE) rail pads (PTRP). However, the rail pad of the traditional structure has an obvious stress concentration when compressed and limited damping performance, which severely limits the service life of the rail pad. This study proposes a novel filled damping block mesh-type rail pad (NFDBMTRP) suitable for heavy haul railways. The rail pad has better damping performance than that of the traditional rail pad under the same stiffness condition. When the rail pad is under pressure, its hexagonal mesh structure can ensure that the stress distribution of the rail pad is uniform. Meanwhile, the damping block filled in the hexagonal mesh cavity can absorb part of the energy so that the overall stress level of the NFDBMTRP is small, which is beneficial for prolonging the service life of the rail pad. On the basis of the vehicle–track coupled dynamics theory, the C₈₀ truck–track coupled dynamics calculation model was established, and a field test of the heavy haul railway was conducted. The time and frequency domain signals of the rail and sleeper acceleration obtained from the test were compared with those from the simulation to verify the accuracy of the dynamics model calculations. Under the same stiffness (70 kN/mm), the dynamic response differences in the four rail pads were compared and studied. The dynamic calculation results showed that the NFDBMTRP not only has smaller acceleration than that of the other three rail pads on the rail, sleeper, and car body but also has the smallest wheel–rail vertical force and derailment coefficient. This implies that improving the damping of the rail pad is beneficial for improving the safety and stability of train operation and has a certain protective effect on the under–track structure. To sum up, the NFDBMTRP has better structural properties and vibration damping performance compared with the traditional rail pad, and has broad application prospects in the heavy haul railway fastening system.