Design and Manufacturing Technology of Round Samples for Studying the Effect of Defects on the Mechanical Properties of Welds

Abstract

The analysis of official data shows that the average service life of a ship in Russia exceeds 25 years, but it is no secret that a significant part of all ships is operated beyond the standard period. The ability of ship structures to withstand fatigue damage (cracks) from variable loads and extreme load damage (cracks, plastic deformations and loss of stability due to violation of their shape) is a complex concept that determines the strength of the entire welded hull. When repairing a ship, hull work accounts for up to 30% of the total repair and is carried out in difficult working conditions. The cost of hulls repairing is high not only because of the basic material costs, but also because the ship is decommissioned for a long time. Additional work on the repair of welds defective sections increases the time and complexity of the construction as well as ships repair. In this regard, the authors of the article consider it necessary to establish dependencies showing the mutual influence of defects in welded steel joints, the parameters of cyclic loading and the duration of the stages of fatigue failure. For this purpose, the authors analyze the cases of destruction of welded structures from welding. The choice of research methodology and materials for the study is justified. To study the effect of internal weld defects on the fatigue strength, the optimal number of test samples is taken. In connection with the specificity of the tasks to be solved, the authors were tasked to develop a scheme and design as well as to manufacture an experimental installation for conducting fatigue tests.