Crack Growth Simulation and Residual Life Assessment of Freight Wheel

摘要

Typical fatigue cracks at wheel web holes propagate under a combination of mechanical forces and braking thermal loads. The stress intensity factors (SIF) for different crack sizes are calculated using the approach of 1/4 node displacement and sub-model techniques. The commercial finite element code ANSYS is used for modeling and 3-D prismatic quarter point 20-node isoparametric degenerate singular elements are adopted for the region near the crack tip. Models on fatigue crack growth and residual life prediction are presented with help of Forman equation. Values of crack growth rate and residual life for a wheel worn by 20mm are finally given.The study indicates that the combination of mechanical forces and grade-braking thermal loads lead to the crack growth of the web hole and the propagation period of the crack less than 15mm can be ensured 3 years at least with the routine inspections. This provides fundamental data for setting up inspection plans and assessing the replacement period of the wheel.