On the fatigue strength calculation of the welded shell structures from high-strength steels under low-cycle loading. Part 2: Development of the assessment methodology

The first part of this work substantiates the procedure for estimating the number of cycles before the appearance of a detectable fatigue crack in weld joints (stress concentrators) which are the usual places of crack occurrence in the absence of major technological defects. It is based on a physical model of the initial stage of fatigue failure, generalized data on the fatigue failure resistance of high-strength steels and their welded joints and FEM calculations. It is reduced to interpolation formulas summarizing the results of numerical modeling. This (second) part of the study presents information necessary to perform practical assessment of fatigue strength in the field of low-cycle loading, including the choice of reserve coefficients when calculating the resource of welded structures. The results of the assessments are compared with the data obtained during fatigue tests of welded joints of large thicknesses performed by multi-pass welding.