CALCULATION DEPENDENCIES FOR DETERMINATION OF THE ENERGY J-INTEGRAL

It is known that crack defects exist in the machines initially. All that requires the creation of analysis methods that allow  to research the propagation of cracks under real loading conditions based on the mechanics of destruction. Widely used criteria for these cases are stress intensity factor, J-integral and crack opening criterion. This paper discusses numerical research of the J-integral determination by finite element method for typical samples that simulating behavior of welded joints. Samples with edge and center cracks are considered as such samples.  The expressions for the J-integral in typical welded joints are obtained from the positions of regression and correlation analyses, based on the planning of machine experiments.  These expressions are depending on the geometry of cracks, external load and material parameters. A number of methodological examples for determining destructive stresses have been solved. Limits of application of linear fracture mechanics for typical samples with edge and center cracks are determined. Influence of residual stresses on value of J-integral in typical samples is estimated. Thus, regression dependencies for determining the J-integral have sufficient reliability and can be used in the practice of predicting the residual life of welded steel structures.