T形焊接接头低周疲劳寿命预报方法研究OA

To accurately predict the low-cycle fatigue life of T-welded joints under bending loads,an equivalent structural strain method integrating the material's true stress-strain constitutive relationship and stress triaxiality was developed.A numerical calculation model for structural strain at the weld toe was derived,and a solution program based on the radial return mapping method was developed using MATLAB.Low-cycle fatigue tests on high-strength steel T-welded joints were conducted with an SDZ-1000kN electro-hydraulic servo testing machine.Furthermore,co-simulations employing ABAQUS and Fe-Safe were performed to comparatively evaluate the life predictive accuracy of the equivalent structural stress method and the equivalent structural strain method.Results show that the equivalent structural strain method,considering strain hardening in the plastic stage,controls the life prediction error within 15%,significantly outperforming the equivalent structural stress method(maximum error exceeding 30%),with all results falling within the two-times standard deviation band of the ASME standard master E-N curve.The results demonstrate that the equivalent structural strain method can accurately assess the low-cycle fatigue life of T-welded joints,taking into account both engineering safety and economic efficiency,and provides a reliable reference for the fatigue design of related welded structures.