Modeling of vertical split rim cracking in railroad wheels

Vertical split rim cracking, due to rapid unstable propagation of a shallow sub-surface crack parallel to the front rim face, is one of the dominant mechanisms of railroad wheel failure. Wheel impact load is believed to be a trigger for this unstable crack growth. This rapid crack growth rate depends on several factors, such as wheel geometry (wheel diameter and rim thickness), load magnitude, load location, residual stresses in the rim, worn tread profile, and material defects in the rim (size, shape, location, and orientation). This paper develops a computational methodology to investigate the effect of these parameters on vertical split rim cracking, using finite element analysis and fracture mechanics. Vertical split rim cracking is modeled using a three-dimensional, multi-resolution, elastic-plastic finite element analysis. Material defects are modeled as mathematically sharp cracks. Wheel impacts are simulated by applying high mechanical loads on the tread surface. The residual stresses and wheel wear effects are also included in modeling vertical split rim cracking. The proposed computational methodology can help to predict whether a vertical split rim failure might be triggered for a given set of parameters, such as load magnitude, load location, wheel diameter, rim thickness, residual stress state, crack size, crack location, and crack orientation. (C) 2011 Elsevier Ltd. All rights reserved.