Meso to macro connections to capture fatigue damage in cemented materials

Abstract

Fatigue-induced damage is a common issue in cemented materials, involving the progressive formation and complicated propagation of fatigue cracks. These cracks typically localise on weak or fracture planes, leading to inhomogeneous deformation within the material. Thus, accurately predicting the fatigue phenomenon becomes challenging due to the material’s inhomogeneity and the complex evolution of cracks, from initiation to propagation and eventual failure. To address this challenge, this paper presents a constitutive model that accounts for strain discontinuity across fracture planes by employing kinematic enrichment. This enhancement facilitates interaction between the material responses of cracks and the outer bulk, thereby contributing to the overall macro behaviour of the materials. Moreover, the proposed model incorporates a new cohesive-frictional fatigue model that couples damage mechanics and bounding surface plasticity to describe the fatigue behaviour of fracture planes/cracks. Since the proposed model features a characteristic length scale, it exhibits size-dependent behaviour and helps overcome the issue of mesh dependence. The model's validity is demonstrated through its ability to capture nonlinear fatigue damage under constant/variable cyclic loading and to simulate the propagation of fatigue fracture process zones. Furthermore, the model effectively captures the significant influence of stress amplitudes on the fatigue lives of materials, making it an essential tool for predicting and mitigating fatigue-induced damage in cemented materials.