Behaviour of supported and unsupported insulated rail joint under different preload conditions

Insulated rail joint is a critical component of the railway track due to its intrinsic conformation and technical characteristics and requires particular attention in the recognition and analysis of possible deterioration during operation. In this work, FEM analysis has been conducted to investigate the mechanical behaviour of the joint by simulating the load induced by the transit of a train. A comparison has been made in the study of insulated four-hole joints between the behaviour of suspended joints, i.e. when the gap between the two adjacent rails is in the middle between two sleepers, and supported joints, i.e. when the joint is positioned on a single or double sleeper. For both scenarios, the optimal operating condition is studied, in which the bolt preload is that specified at the joint installation phase and the condition of progressive deterioration due to operation is simulated by partially reducing the amount of preload. The purpose of this analysis was to examine the mechanical response of the joint between the two support conditions to compare the two scenarios in the event of loss of bolt preload.