Design method for improving limiting sensibility of eddy current detection by using resonant frequency change

Abstract

The invention discloses a design method for improving the limiting sensibility of eddy current detection by using a resonant frequency change. A quartz crystal oscillator in an eddy current detection instrument is replaced with a frequency generated by a resonance circuit; an eddy current detection coil is used as an inductor part of the resonance circuit; the eddy current detection instrument designed through the method can obtain a resonant eddy current detection impedance signal chart comprising amplitude, phase and frequency information; the eddy current detection instrument has the work characteristics of a first generation of resonant eddy current instruments, meanwhile, has the advantages of a second generation of impedance plane analysis eddy current instruments; the limiting sensibility of the eddy current detection is further improved through the combination of the two mechanisms.

Description

Technical field [0001] The invention relates to a design method of a non-destructive testing instrument, in particular to a design method for improving the limit sensitivity of eddy current detection by changing the resonance frequency. Background technique [0002] Eddy current testing is a non-destructive testing method based on the principle of electromagnetic induction and is suitable for conductive materials. When a conductor is placed in an alternating magnetic field, an induced current will be generated in the conductor, which is called eddy current. Due to changes in various factors of the conductor itself (such as electrical conductivity, magnetic permeability, shape, size and defects, etc.), it will lead to changes in the induced current. This phenomenon is used to judge the nature, state and defect detection method of the conductor. , called the eddy current testing method. [0003] During eddy current testing, the conductor is brought close to the coil with alt...

AI Technical Summary

Problems solved by technology

[0010] To sum up, the commonly used quartz crystal oscillator in conventional eddy current testing instruments has good frequency stability, high Q value and narrow bandwidth; however, the frequency cannot be adjusted and is only suitable for fixed frequency work.

For the detection of some special occasions, in order to change the detection frequency, only the open-loop method of frequency division can be used to adjust, so it is impossible to use the frequency offset characteristic signal generated by material discontinuity in actual detection

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