Modeling and Simulation of Fatigue Crack Initiation Process Based on Field Theory of Multiscale Plasticity (FTMP): Part I: PSB Ladder Formation and Verification

In this study, we successfully reproduced the persistent slip band (PSB) with laddered patterning, showcasing the predictive capability of the framework of Field Theory of Multiscale Plasticity (FTMP) without relying on ad hoc models, intricate mathematical models, or elaborate finite element discretization. The FTMP-incorporated CP-FEM simulation not only reasonably replicates the experimentally observed laddered morphology and PSB but also effectively simulates surface roughening and grooving, independent of vacancy formation and diffusion. These results highlight the significance of laddered morphology and set the stage for further investigations into the effects of vacancy formation, as extended in the subsequent paper. Leveraging incompatibility tensor-based degrees of freedom, the FTMP framework offers exceptional capabilities for natural modeling dislocation substructures typically overlooked in conventional approaches, positioning it as a transformative tool for advancing our understanding of the mechanisms that dictate slip band-fatigue crack transitions.