Fatigue crack growth analysis using a coupled approach of 3D peridynamics and 1D high-order refined elements

To efficiently simulate 3D fatigue crack nucleation and growth, this paper incorporates a peridynamic (PD) fatigue model into a coupled local/non-local computational framework. In the critical damage zone, fatigue degradation is described by a 3D bond-based PD model equipped with a remaining-life bond degradation law. Outside this zone, the surrounding intact structure is represented by 1D higher-order finite elements based on the Carrera Unified Formulation (CUF), thereby improving computational efficiency. The two domains are coupled through overlapping regions and Lagrange multipliers, which preserve displacement compatibility and suppress spurious interface softening. The framework is validated through three benchmark problems, namely an hourglass specimen for fatigue crack nucleation, a compact tension specimen for stable fatigue crack growth, and a curved middle-tension specimen of engineering interest. The results show that the method can reproduce the main features of 3D fatigue fracture, including S–N trends, Paris-law crack-growth behavior, and crack paths. By adopting an appropriate local/non-local modeling strategy, the total number of degrees of freedom (DOF) is reduced by 30.2%, 74.6%, and 93.1% for the three benchmark problems, respectively. These results demonstrate that the proposed CUF-PD framework provides an efficient approach for 3D fatigue fracture simulation at a markedly reduced computational cost.