Reasons for failure of railway fittings fishplate

The interaction between the fishplate and the rail, the actual load on the fishplate and the material of the fishplate determine the location, time, mode and rate of the fishplate damage, and the interaction condition mainly affects the origin of the crack. Location and time, loading conditions and material conditions more determine the way and rate of crack growth. When the crack starts from the top of the fishplate, the crack initiation and propagation are more affected by the material because of the small tensile stress; when the crack starts from the bottom of the fishplate, the tensile stress it receives is larger, Crack initiation and propagation are more affected by load.
Season is also an important factor in fishplate failure. Judging from the field use, the damage of fishplates in winter is significantly higher than that in other seasons. Through the measurement of the cold and brittle temperature of the fishplate, it can be seen that the impact value of the widely used B7 material fishplate has been measured at the lower platform in the range from -60°C to room temperature, so it can be considered that the cold and brittle temperature of the material is not the cause. The main reason for a large number of fractures of fishplates in winter.
Further analysis shows that the fracture of the fishplate in winter may be related to the change of the rail gap in winter. The increase of the rail gap in winter will increase the tensile stress of the fishplate, especially in the middle of the third and fourth bolt holes. This additional stress will cause fish Increase in the number of tailgate failures. However, due to the absence of systematic data on the magnitude of the additional stress, its influencing factors and the threat to the life of the fishplate, further conclusions cannot be drawn.
In addition, it is worth mentioning that some fishplates for special purposes or for special parts, such as special-shaped fishplates, fishplates at the toe or fishplates used in tunnels, due to the more complicated stress state, It is more difficult to maintain, and it is often affected by some corrosive air, so the failure rate is often higher than that of ordinary fishplates, and the damage to the line is also greater, so it should be paid enough attention.