Abstract:
Developing nonlocal modeling methods represented by peridynamics helps overcome the singularity bottleneck encountered by traditional continuum mechanics methods when solving discontinuous problems. In this study, both the standard and improved models of bond-based peridynamics were derived, and the expression of the peridynamic micromodulus was presented based on the equivalence of elasticity tensors. On this theoretical basis, the free vibration and fatigue damage behavior of homogeneous thin plates were simulated. Through the vibration analysis of slender beams and homogeneous thin plates, as well as the fatigue analysis of dumbbell-shaped specimens, the convergence and effectiveness of the peridynamic models were verified, which provides a reliable foundation for the subsequent coupled analysis. The numerical simulation results indicate that cracks can reduce the modal frequencies of structures, and the angle of initial cracks can exert a significant influence on modal shapes. Fatigue damage accumulation causes the evolution of modal characteristics of thin plates. To investigate such fatigue effect, the fatigue damage and dynamic characteristic evolution laws of thin plates were compared under two loading conditions: using updated first mode displacement and using non-updated first mode displacement for fatigue loading. The results show that the global damage and modal frequency reduction caused by the former may reach more than twice those caused by the latter, indicating an obvious coupling relationship between vibration and fatigue. Neglecting the vibration-fatigue coupling may significantly underestimate the accumulated fatigue damage and the degradation of dynamic properties. From the perspective of numerical simulation, this paper demonstrates the necessity of conducting vibration-fatigue coupling analysis of structures and the feasibility of peridynamics in vibration-fatigue coupling analysis of structures. The present work thereby provides a certain reference for subsequent study on vibration-fatigue coupling analysis of more complex composite structures, in which material anisotropy, interface effects, and multiple failure modes will further complicate the coupling behavior.