DIAGNOSTICS OF RESIDUAL STRESSES AND ESTIMATION OF THEIR INFLUENCE ON THE STATIC STRENGTH OF WELDED JOINTS OF PIPES WITH DIFFERENT THICKNESSES WITH CRACK-TYPE DEFECTS

摘要

Within the framework of the calculation-experimental method suggested by Pidstryhach and his followers, a mathematical model for definition of residual stresses in the zone of circular welded joints of pipes with different thicknesses is developed. We constructed a functional to determine the residual thermoplastic strains on the basis of theoretical relations and experimental data obtained by a nondestructive (semidestructive) methods. Using the two-parametric criterion R6 of fracture mechanics and a failure assessment diagram constructed on its basis, the strength reserve coefficients of a welded joint of the main pipeline with different thicknesses under internal pressure and the presence of a surface crack in the thinner pipe wall are determined. The influence of residual stresses on the strength reserve coefficients is estimated.