On-line detection method for low cycle fatigue cracks of turbine disk based on Nyquist diagram

Abstract

The invention discloses an on-line detection method for low-cycle fatigue cracks of a turbine disk based on a Nyquist diagram. In a low-cycle fatigue test of a turbine disk, the radial displacement vibration signal of the wheel disk shaft and the key phase pulse signal are obtained online; Synchronous averaging is used to preprocess the vibration signal of the radial displacement of the wheel shaft to remove the white noise contained in the signal; the real part and imaginary part of the crack index at different speeds are extracted from the denoised signal by using the full-period discrete Fourier transform , use the real part and imaginary part of the crack indicator in the loading process and unloading process to draw the crack indication Nyquist diagram; then judge whether there is a crack in the turbine disk by whether the loading curve and the unloading curve cross in the crack indication Nyquist diagram. The invention can realize the on-line detection of disc cracks during the low-cycle fatigue test of the turbine disc and improve the test safety. At the same time, it does not need to be stopped for disassembly and inspection during the low-cycle fatigue test, which can shorten the test period and reduce the test cost.

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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