Turbine disc low-cycle fatigue crack online detection method based on Nyquist diagram

Abstract

The invention discloses a turbine disc low-cycle fatigue crack online detection method based on a Nyquist diagram. The method comprises the following steps: acquiring a wheel disc axial radial displacement vibration signal and a key phase pulse signal online in a turbine disc low-cycle fatigue test; preprocessing the radial displacement vibration signal of a wheel disc shaft by using angular domain synchronous averaging, and removing white noise contained in the signal; extracting real parts and imaginary parts of the crack indexes at different rotating speeds from the denoised signals by adopting full-period discrete Fourier transform, and drawing a crack indication Nyquist diagram by utilizing the real parts and imaginary parts of the crack indexes in the loading process and the unloading process; and judging whether the turbine disc has cracks or not according to whether a loading curve intersects with an unloading curve in the crack indication Nyquist diagram. According to the invention, online detection of the cracks of the wheel disc can be realized in the low-cycle fatigue test process of the turbine disc, the test safety is improved, shutdown disassembly and assembly 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 detection method for low-cycle fatigue cracks of a turbine disk based on a Nyquist diagram. Background technique [0002] Aero-engines are an important factor restricting the development of my country's aviation industry, especially the life and reliability of aero-engines. Some foreign advanced engines, such as F-110 and F-136 engines, have a full life span of 6,000-8,000 and 13,000 hours respectively, while existing engines generally have a full life span of 1,000-2,000 hours. [0003] Turbine disk is one of the key parts of aero-engine, which has an important impact on the life of aero-engine, so it is very important to find out the life of the wheel in the process of engine design. The current common method is to determine the service life of the wheel by discontinuous decomposition detection in the low cycle fatigue test. However, ...

AI Technical Summary

Problems solved by technology

However, this method requires repeated shutdowns, resulting in an excessively long test cycle, increasing test costs, and affecting the overall development cycle of the aero-engine

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