Dynamic behaviour of railway fastening setting pads

Thermoplastic elastomer railway pads, placed between the base of the steel rails and the prestressed concrete sleepers, play a major role in the general maintenance of the state of the overall structure of a railway line. These rail setting pads provide the elasticity of the line and damp the vibrations which the rail transmits to the sleeper, thus avoiding the cracking of the concrete sleepers and preventing the wear and tear of the ballast. They also provide electrical insulation between the rails.This paper describes a test methodology for determining the dynamic behaviour of railway fastening setting pads in working conditions, which may involve a wide range of temperatures associated to the wear and the hardening they undergo during the cyclical load process applied on them caused by the passing of the trains. To this end, measurements of the evolution of the stiffness of the pads have been made, both static and dynamic. Also associated energy parameters have been measured, establishing an index of the degree of deterioration undergone by these pads.