Failure Analysis of Fatigue Cracking in the Tension Clamp of a Rail Fastening System

摘要

Fatigue cracking was recently discovered in the tension clamp (SKL15) of a rail fastening system during its service life. Here, the fatigue strengths of SKL15 and SKLB15 (used for replacement) tension clamps were assessed using field measurements and finite element analyses. The strain and displacement of these tension clamps were measured both in a laboratory and at the section of railway track where the original fatigue cracking occurred. Due to limited access to the exact crack initiation location, the strain gauge was instead installed nearby. Finite element analysis was conducted to obtain the stress conditions at the crack initiation location. Extremely high stresses were produced after the installation of tension clamps SKL15 and SKLB15, and this allowed small stress amplitudes for fatigue cracking. The fatigue strengths of the clamps were evaluated using Goodman and Gerber curves. The stress amplitude of the SKL15 was greater than the allowable stress amplitude, presenting the possibility of fatigue cracking.