A Pulsed Eddy Current Detection System in Underdamped State

Abstract

The invention discloses a pulsed eddy current detection system in an underdamped state. The detection system uses a low-frequency pulse signal with a fixed frequency as an excitation signal, and through a specially designed pulsed eddy current sensor in an underdamped state, it is ensured that the system output response signal is a sine wave signal with attenuated amplitude. , the first peak of the signal is in an overshoot state, which effectively amplifies the defect signal; the excitation frequency of the system remains unchanged, and it is only necessary to replace the underdamped pulse eddy current sensor with different parameters to generate sine waves of different frequencies in the excitation coil. Wave signal, so as to obtain the detection effect similar to that of multi-frequency eddy current detection, so that the pulsed eddy current detection system can also suppress the interference signal through frequency adjustment and improve the signal-to-noise ratio just like the sine wave excitation eddy current detection system. The circuit complexity of the system is greatly reduced; the amplitude-attenuated sine wave signal carries more abundant information, which is convenient for extracting feature quantities by time-frequency analysis and realizing quantitative detection of defects.

Description

technical field [0001] The invention relates to a pulsed eddy current detection technology, in particular to a more definite corresponding relationship between pulsed eddy current signal features and defects in an under-damped state, specifically a pulsed eddy current detection system in an under-damped state. Background technique [0002] Pulsed eddy current testing technology, referred to as PEC, is one of the new nondestructive testing technologies that have developed rapidly in recent years. In traditional eddy current testing, a single-frequency sinusoidal signal is used as an excitation, and defects are identified by analyzing the voltage value and phase angle of the testing signal. The eddy current selects a square wave signal with a certain duty cycle as the excitation signal, and determines the defect-related information through the analysis of the time-domain response of the transient induction magnetic field. The time-domain information is used as a feature quanti...

AI Technical Summary

Problems solved by technology

[0004] Although the pulsed eddy current non-destructive testing technology has many advantages and has shown a wide application prospect, it also has technical limitations, which are manifested in: it is impossible to get rid of the influence of the lift-off effect on the test results in the eddy current test; the theory Although the foundation has been established, there is still not a sufficiently comprehensive and systematic evaluation system, and the mapping relationship between defects and feature quantities is still not complete, which limits the use of pulsed eddy current testing in some specific environments

In addition, because pulsed eddy current testing determines the defect-related information by analyzing the time-domain response of the transient induction magnetic field, and the change of the transient response signal caused by the defect is often very small, so the signal quality requirements of pulsed eddy current testing The external environment often leads to signal disorder or clutter. In order to ensure the accuracy of the detection, not only must the signal be pre-processed such as denoising, but also bring more stringent requirements to the entire detection system, resulting in The entire detection system has become complicated, and the overall detection system is not yet perfect

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