Wheel fracture - Sensitivity to extreme loads for two generic wheel designs
Paper in proceedings, 2013
The web (disc) of railway wheels is generally designed with respect to mechanical loading by use of standardized load cases. These are assessed using fatigue criteria aiming towards an infinite life. This system of design loads and implemented fatigue criteria has successfully been used over the years and has resulted in that only a very limited number of web failures are reported. Nevertheless, wheel webs are occasionally subjected to fatigue related problems. These are many times associated to substantial wheel tread damage which causes excessive forces. At other occasions, root causes are more unclear. In the present paper, the sensitivity to excessive mechanical loading of two generic wheel designs is studied. Evaluation of fatigue sensitivity shows that wheels of low-stress design can be sensitive to tread damage located towards flange side and/or field side of tread. Study of fatigue crack growth in the web of the wheels indicates slow crack growth for normal running conditions. Moreover, a substantial widening of the crack (in the circumferential direction) is required for the crack to grow deeper into the web.