Contact stress variations near the insulated rail joints

Abstract

The effect of an insulated rail joint (IR J) on the contact stress variation near wheel±rail contact zones was simulated by employing three-dimensional ®nite element models. Three linear elastic IR J materials, i.e. epoxy-®breglass, polytetra¯uoroethylene (PTF E) and N ylon-66, were investigated. Contact elements were used to simu late the interaction between the wheel and rail contact points. N umerical results showed that the presence of IR J might signi®cantly affect the wheel±rail contact stress distrib utions. R esults also indicated that the traditional H ertzian contact theory is no longer available to predict the contact stress distribution around the rail joints.

Numerical and Theoretical Investigation of Wheel-Rail Contact

“…The other parts of the track are investigated by some researchers. Contact stress distributions for the three joint materials near the insulated rail joints is investigated with the three-dimensional finite element model established by Chen and Kuang [10]. They specified that the insulated rail joints effect the contact stress distribution and Hertz contact theory is impracticable for near insulated rail joints.…”

Health condition monitoring of insulated joints based on axle box acceleration measurements

“…The joint bars are attached to the rails by bolts and epoxy adhesive. The IRJs are characterized by high impact dynamic forces at the wheel/rail interface [40], caused by the combination of two factors: lower bending stiffness of the joint bars comparing to that of the rail, leading to larger deflection [10,13]; and lower values of the Young's modulus of the endpost comparing to the one of the steel [2]. The impact dynamic forces may have several consequences on the state of an IRJ, such as the resulting high stress concentration producing plastic deformation of the rail surface [11]; ''cavity-like" damage appearing in the rail head after the gap [34]; the high maximum shear stress leading to the partial loss of the bond between the joint bars and the rail [9], and the contribution to the growth of cracks starting from the holes in the rail [22].…”

Experimental Investigation Into the Condition of Insulated Rail Joints by Impact Excitation

“…For instance, regarding the vehicle, higher speed and higher axle loads accelerate the degradation of IRJ [3]. With respect to the track, higher wheel-rail impact forces occur with increasing misalignment between the rail ends [4][5][6], stiffer railpads [7], increasing deflection between the two rails [8][9][10][11]43] and smaller Young's modulus of the end-post [12]. These studies have given an insight into the wheel-IRJ interaction.…”

“…The vehicle/wheel-IRJ/track interaction is a complex system. In many of the existing models, simplifications are made when representing the track, such as not accounting for the contact between rail and plates [3,8,12,13] or simplifying the track to only one rail section [4,6]. However, little is known about the consequences of these simplifications because, until recently, few measurements were available for the validation of IRJ models.…”