RESEARCH ON THE INFLUENCE OF BALL TREATMENT IN THE MAGNETIC FIELD OF THE BLADES WITH OPERATIONAL DAMAGES ON FATIGUE STRENGTH

Purpose. Research the effect of ball treatment in a magnetic field on the blade tips, which have varying degrees of blade tip damage in operation, on their endurance limit. Research methods. Mechanical method for studying residual stresses, experimental method for determining blade endurance, stepwise regression methods for building regression models. Results. On engine blades that operated under different conditions and had different service life, the greatest wear was observed in the peripheral part of the blade (cross sections A7-A7 and A8-A8). Processing blades from various engines with operational damage with balls in a magnetic field significantly increases the resistance of the blades to fatigue, the endurance limit of the blades increases from 14 to 22 %. Regression models of natural oscillation frequencies and blade life were constructed. The obtained regression models showed that the greatest influence on the natural oscillation frequency of blades is not only the operating conditions and blade geometry, but also the amount of life, the hardness of the initial blade and the ultimate strength of the blades. Operation of helicopter engines in conditions of increased dustiness and abrasive wear requires the application of protective coatings with high erosion resistance to the upper section of the blade back. Additional application of surface hardening methods provides increased reliability, fatigue strength and extended service life of the gas turbine engine. Scientific novelty. A method has been proposed that allows for effective processing of blade back with damage that occurred during operation, which ensures an increase in their durability and reliability. As a result, endurance indicators increase and the service life of parts is extended. Practical value . The obtained experimental data provide grounds to recommend the method of treating blade tips with steel balls in a magnetic field as a technological operation for repairing compressor blades that have undergone operational damage such as potholes on the leading edges.