Computational Modeling-Based Estimation of Residual Stress and Fatigue Life of Medical Welded Structures

In order to improve the fatigue reliability of medical welded structures in service, a multi-physics field modeling framework based on heat-force coupled finite element and fatigue damage theory was constructed to quantitatively analyze the residual stress and fatigue life of 316L stainless steel welds. The results show that the predicted life of lap weld is 22.8×10³ cycles, which is 50.5% lower than that of cross weld under the condition of heat input density of 2.6×10⁸ W/m³ and principal stress gradient up to 85.3 MPa/mm. The error between the model and the measured data was controlled within 6%, and the R² was up to 0.988, which verified the applicability of the modeling system. It is analyzed that the stress gradient and structural geometric features have a significant effect on the fatigue life, and the parametric model can provide a theoretical basis for the reliability design of medical structures.