Finite Deformation Analysis for Fatigue and Creep‐Fatigue Evaluation Under Cyclic Thermo‐Mechanical Loading

This study develops a cyclic thermo‐elasto‐plastic creep constitutive model within a finite‐deformation framework for structures under cyclic thermo‐mechanical loading. The A‐K‐O kinematic hardening model is combined with a Norton‐Bailey creep law, and the governing equations are discretized using a backward‐Euler return‐mapping algorithm. A consistent tangent stiffness matrix is derived to improve the convergence of nonlinear finite element analyses. Plastic dissipation is further introduced as an internal heat source in a sequentially coupled thermo‐mechanical formulation. Numerical examples show that the finite‐deformation formulation captures large plastic deformation more accurately than the small‐deformation assumption, that creep during load holding promotes ratcheting and stress redistribution, and that plastic dissipation under rapid cyclic loading produces substantial temperature rise. The proposed framework provides a stable numerical basis for evaluating deformation and heat generation in components under cyclic thermo‐mechanical loading.