Online monitoring method for low-cycle fatigue crack of aero-engine turbine disc

Abstract

The invention discloses an online monitoring method for a low-cycle fatigue crack of an aero-engine turbine disc. An eddy current displacement sensor and a key phase sensor are arranged on a wheel disc shaft of a low-cycle fatigue tester of the aero-engine turbine disc so as to acquire a wheel disc shaft radial displacement vibration signal and a key phase pulse signal on line; a vibration signalof the wheel disc at a preset rotating speed in each load cycle is obtained; a real part and an imaginary part of the crack index are extracted from the vibration signal by adopting full-period discrete Fourier transform; and crack indexes of a plurality of cycles at the beginning of the test are selected as baselines, relative amplitudes and relative phases of the crack indexes are formed by obtaining vector differences to the baselines in the subsequent cycles, an alarm threshold is set according to a 3sigma criterion, and the fatigue crack of the turbine disc is monitored. According to theinvention, damage to the tester caused by burst of the wheel disc is avoided, shutdown inspection in the low-cycle fatigue test process is not needed, the test period can be shortened, and the test cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of aero-engine fault diagnosis, and in particular relates to an online monitoring method for low-cycle fatigue cracks of an aero-engine turbine disc. Background technique [0002] As one of the three major components of an aero-engine, the turbine works under the conditions of high temperature, high pressure and high speed, and bears combined alternating loads such as centrifugal force, thermal stress, aerodynamic force and vibration stress, as well as corrosion and oxidation of the environmental medium. , making the turbine the most vulnerable part of the aero-engine, and its life is the main factor restricting the overall life of the engine. Turbine disk is one of the important rotating parts in the structure of aero-engine, and its main function is to install turbine blades to transmit power. Most of the fracture failures of turbine disks will cause non-containment damage, and the consequences are often ...

AI Technical Summary

Problems solved by technology

[0003] At present, in the fatigue life assessment test of aero-engine turbine discs, non-destructive testing methods such as hole detectors, phosphor penetration, ultrasonic waves, and eddy currents are mainly used to detect cracks, and intermittent crack detection inspections lead to long test periods and high costs.

Not only does it affect the overall development cycle of the engine, but also the turbine disk is still at risk of bursting during inspection intervals

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