Improved Hashin criterion for fatigue life prediction of composite drive shaft considering stiffness degradation

A dynamic cycle-jump progressive fatigue framework for the evaluation of composite drive shafts was established by integrating an improved 3D Hashin progressive damage model with an empirically calibrated S–N master curve. Instead of relying solely on static stress analysis, a mathematical cycle-jump algorithm is implemented to dynamically track cumulative fatigue damage and nonlinear stiffness degradation over the entire lifespan. In this approach, high-fidelity finite element simulations were executed under ultimate torsional loads to extract a stabilized post-damage stress field. The 3D stress tensors were then mapped using a Tsai–Hill equivalent formulation to penalize matrix-dominant failure modes. The results demonstrate that superior layups incorporating strategically oriented plies, successfully mitigate severe transverse matrix compression and significantly reduce the multiaxial equivalent stress. This physically grounded stress relaxation, coupled with the dynamic stiffness degradation analysis, exponentially extends the fatigue life into the high-cycle regime, providing an efficient and physically consistent tool for the advanced durability design and refinement of composite transmission structures.