Performance assurance of mechanical engineering construction in the existence of cracks

Abstract

The purpose of this paper is to consider the development of engineering ways of preventing the further development of through cracks in the sheet elements of the complex technical structures. The latest individual approach to the assessment and assurance of performance of structures with cracks, which is to take into account the features of their operation, has been applied in this work. Preference is given to methods that reduce the concentration in the danger zone. Studies have shown that the most appropriate and effective ways to prevent the further development of a through crack are the structural methods and combinations of the structural and technological methods. The effectiveness of these methods was determined on the basis of the strength uniformity approach of structural elements with a crack. The criterion of strength uniformity from the position of fatigue and brittle strength with an error on the safe side is the value of theoretical stress concentration factor [K]. The[K] value was made on the basis of generalization and analysis of cases of crack formation, the results of tests of typical components of hull structures and welded joints. The safe concentration of stresses near the holes of various purposes in the members of the machine-building structures is in the range from 2 to 4. Taking into account the relevant requirements for the ratio of the radius of curvature and the width of the cutout, we obtain 3.5. The value of the criterion К1 is determined by the ratio of the calculated crack length to the diameter of the hole drilled at its ends and the location of the crack.