A dual boundary element method-based framework for prediction of fatigue crack growth in layered and graded halfspaces

A dual boundary element method (DBEM)-based framework for predicting fatigue crack growth in layered and graded halfspaces is established in this study. The framework integrates automated mesh generation, a DBEM-based solver for the crack-tip stress intensity factor (SIF), and the crack growth prediction. This integrated system automates the entire analysis workflow of the fatigue crack growth in layered and graded halfspaces, eliminating the need for laborious manual modeling and significantly enhancing computational efficiency. The validity of the proposed framework is verified using benchmark cases of a penny-shaped crack embedded within a layered halfspace subjected to internal pressure and far-field uniform tensile stress on the external boundary surface. Regarding cyclic load distribution, the analytical methodology is applicable to fatigue crack growth driven by both externally applied tensile stress (on the external boundary surface) and internal pressure (on the crack faces). In terms of crack location classification, the method is suitable for analyzing cracks situated at the interface between dissimilar materials within a halfspace and cracks distributed within layered and graded halfspaces. Furthermore, the framework enables the systematic investigation of the influence of critical factors such as the loading protocol, the elastic modulus gradient of the graded material, and the initial crack shape on crack growth behavior. According to results of parametric analyses, the SIF at the tip of interfacial cracks within the functionally graded materials (FGMs) can be effectively reduced by strategically tailoring the elastic modulus gradient distribution. Subsequently, this reduction in SIF directly enhances the fatigue life of FGMs.