Theoretical and Experimental Studies of Intermediate Rail Fasteners

Purpose: To analyze international experience in detecting the causes of the intermediate rail fastener failure. Currently, quite a lot of rail fastener designs have been developed for various operating conditions and many computational and laboratory methods for determining their operability have been created. At the same time, the issue of predicting and verifying the service life of the rail fastener and maintaining its vibration resistant properties remains open. Methods: Comparative analysis of computational models for determining the stress state of intermediate rail fastener elements; laboratory and field tests in various operating conditions. The results of cyclic fatigue bench tests do not always agree with the results of in-situ tests on a railway line in operation. At the same time, failures of rail fasteners different types occur due to the failure of different elements of the fastener assembly. The article discusses the issues of maintaining the vibration resistant properties of rail fasteners in service, the causes of fastener failure and the issues of service life verification. Results: An elastic clip has been identified as the element causing the majority of the entire fastener unit failures. Research papers claiming that the resonance vibration due to rail undulatory wear is the main cause of the elastic clip failure have been considered, as well as those claiming that the clamp failure is due to increased axle loads. Practical significance: The foundations have been laid for the development of measures to reduce or prevent the destruction of elastic clips of intermediate rail fasteners in service.