Simulation of Railroad Crack Growth Life under the Influence of Combination of Mechanical Contact and Thermal Loads

One of the most important issues in railroad wheels is residual stresses. It is desirable to produce less residual stresses when possible and to decrease the remaining residual stresses in the wheels. The goal of this paper is to predict the crack propagation detail in a railroad mono-block wheel in the presence of residual stress induced by manufacturing process and service conditions. A 3-D elastic-plastic finite element analysis, using the ANSYS/PDS tool is used to estimate the residual stress field and also the superposed alternating rolling contact stresses in a mono-block wheel. A three-dimensional finite element procedure is developed for analyzing fatigue crack growth in the wheels by using Franc3D software. Fracture mechanics is used to predict the crack growth life developed from a two-stage fatigue loading cycle where both mechanical loads and thermal loads are present. The results revealed that crack growth life is highly sensitive to the residual stress. Therefore, this factor significantly affects the crack growth life of railroad wheels during service conditions. In the present investigation, a number of parameters such as the axle load, crack size and coefficient of friction are studied using the proposed model.