Fatigue Crack Modeling of Railheads Using a Nonlinear Cohesive Zone Model

ABSTRACT Subsurface fatigue crack growth within railheads can be deleterious leading to catastrophic failures in rails. This study aims to model the fatigue crack growth originating at the subsurface level within railheads. Towards that end, a finite element modeling approach is utilized wherein complex crack growth is explicitly modeled using a nonlinear cohesive zone (NCZ) model for the first time. The modeling demonstrates the capability to effectively simulate fatigue crack growth in rails. The parametric analysis conducted within this study indicates that the key NCZ parameters are effective indicators of rail fatigue life. It can lead to appropriate fracture characterization for predicting the fatigue crack growth rate and fatigue life of railheads found to contain pre‐existing flaws. Model validation against experimental fatigue data of a rail specimen up to 200,000 cycles demonstrated that the NCZ model can reasonably capture crack growth in railheads, supporting its potential as a robust fatigue life prediction model. The simulated model results obtained herein indicate the feasibility of the NCZ for effectively predicting complex fatigue crack growth in rails induced by subsurface flaws in railheads, thereby potentially leading to an advanced mechanistic tool for predicting the service life of rail sections with properly detected subsurface flaws.