Automated fatigue strength assessment of arc-welded structures according to the Peak Stress Method

Abstract

The Peak Stress Method (PSM) is an approximate, FE-oriented application of the notch stress intensity factor (NSIF) approach to fatigue design of welded joints. This approach is based on the singular linear elastic peak stresses calculated from coarse FE models. The PSM was calibrated by using 2D, four-node plane quadrilateral elements; 3D, eight-node brick elements and 3D, four-node or ten-node tetra elements. By adopting the averaged Strain Energy Density (SED) as a fatigue strength criterion, a design stress, the so-called equivalent peak stress, has been defined and adopted in conjunction with a reference design fatigue curve to estimate the fatigue life of welded structures. The equivalent peak stress has successfully been adopted to assess the fatigue strength of arc-welded joints made of either structural steels or aluminum alloys and subjected to axial, torsion or multiaxial fatigue loadings. In the present work, a subroutine, named ANSYS-PSM, has been developed in the post-processing environment of ANSYS® FE code to automate the PSM for 2D or 3D FE models. After having briefly recalled the theoretical background of the PSM and the procedure to apply it step by step, the paper presents the adopted programming languages and the workflow of the developed subroutine.