Diagnostics of the operational damage to the turbine blades of aircraft engines

Abstract

Diagnostics of damage to the parts of aircraft engines provides valuable information about the causes of damage and guidelines for developing recommendations for prevention of the flight accidents. The use of the results of diagnostics of turbine blade failures in service and analysis of the operating experience gained upon operation of the aircraft engines are the necessary conditions providing high reliability of turbine blades. The goal of the study is analysis of the in service destruction of the turbine blades of aircraft engines, development of methods of damage diagnostics, evaluation of the blade health and vitality, elucidation of the causes of service failures, development of safety recommendations and implementation measures preventing the destruction of the turbine blades in operation. Methods of fractographic and metallographic analysis as well as computational and experimental methods are used to assess the performance and survivability of the blades. The results of the diagnostics of the service failures of the turbine blades of aircraft engines, methodological aspects of the research in determination of the destructive value of the AC voltage amplitude, identification of the sequence of actions of the prevailing damage mechanisms, determination of a decrease in the safety factor of the fatigue strength and the value of the threshold size of crack-like defects for different levels of vibratory stresses, and determination of the duration of the fatigue crack growth are presented. Methodical approaches thus used and results of the service failure diagnostics allowed us to obtain the new data on loading, workability and survivability of the turbine blades, as well as on the impact of the crack-like defects, the growth rate of fatigue crack in service conditions, elucidate the causes of service failures and specify the recommendations for their prevention.