The Failure Analysis Of Two Kinds Of Rail-fastener Springs And Finite Element Analysis

The fastener which connect rails and sleepers to form the track panel it plays an important role to ensure the reliability and stability of the track, and has an important impact on the safety of the railway transport. The type III spring fastener is a new fastener which designed for the high-speed and heavy rail without bolts and shoulder block, it combined with the spring, the embedded iron socket, the insulating stopper and the rail cushion. The SKL15elastic fastener is a high-speed railway fastener with the advantage of high-elastic process. In actual use, as the influence of the friction and wear of the contact interface between the embedded iron seat or bolt and the spring, material properties and so on, the contact area in the force changes, resulting in the spring appears the problem of loosening or fracture failure in its life cycle, the pressure of the fastener system gets smaller, so that the spring becomes failure.This paper makes the failure of the spring as the object of the study, combined with micro hardness tester, optical microscopy (OM), stereo microscope, scanning electron microscope(SEM)and so on, it analysis the failure mechanisms of the spring, and use Solid works and ABAQUS software to simulate and analysis the installation process of the spring fastener, it analysis the response of the fastening system under different work conditions compared with the experimental results, and give some suggestions and preventive measures, The main results were as follows:1. According to the results of this study it show that the heavy wear exists in the contact interface between the spring and the other components; the result offracture failure is surface defects, loose material and stress concentration which promote crack initiation and development, resulting in the fracture of the spring. The machining process of the spring steel should try to avoid the generation of holes inside the material, the surface should try to ensure the smooth, and the use of the spring should pay attention to rust and corrosion. 2.The three-dimensional solid model of the type III spring fastener is established to analysis the stress distribution of the spring, the results showed that:the stress concentration existsin the big arc of the spring where the shear stress is the maximum to promote the formation of micro cracks, the max tensile stress conducive to crack propagation, this position is consistent with the actual results to fracture location.3. The influence of friction andnormal displacement load on Miese stresses of the spring, shear stress, the normal stress of Y direction and buckle pressure. The results showed that:With the increase in the coefficient of friction, the stress in the arc of the spring gradually increased, more conducive to the crack initiation and propagation; buckle pressure gradually reduced, weakened the role of the fastener to track; when the displacement load greater than14mm, the Mises stress of the big arc of spring reaches its yield limit, quickly lead to crack initiation and propagation.