International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The solution to the scientific task of identifying the fundamental laws of surface cracks development during their coalescence in the elements of steel structures under cyclic loading is presented in this article. A simulation model of coalescence of identical coplanar surface cracks has been developed. The model considers the solution to two problems: substantiation of the crack geometry during coalescence, and obtaining calculation formulas for estimating the stress intensity factors along a series of saddle-shaped contours. Based on the definition of stress intensity factors for contours modeling the gradual propagation of cracks in the coalescence zone using the finite elements method, the proposed model was tested to compare the calculated durability with experimental data.

A fracture mechanical behavior of thin-walled elements with through-thickness crack is researched. General analytical methods to determine stress intensity factors (SIF) in such elements are presented. The methods are based on the assessments of nominal stresses in the process of crack growth (first method) and change of inertia moment in defective section (second method). Correction functions are obtained for the central crack under bending for rectangular cross-section of thin-walled beams