A cross-correlation eddy current thermal imaging defect detection and tomography method and system

Abstract

The invention discloses a cross-correlation eddy current thermal imaging defect detection and tomographic imaging method and system. The system can work in the modes of pulse, phase-locking, frequency modulation, and modulation to generate different modulation signals, and generate different excitation signals by modulating high-frequency AC signals to inductively heat the object to be inspected. Time-varying temperature information is used as detection data. Use or generate a specific signal as a reference signal, implement a cross-correlation algorithm on the detection data and the reference signal, realize pulse compression, and obtain matching information such as in-phase, quadrature, amplitude, and phase between the detection data and the reference signal at different times. Extract eigenvalues ​​from the matching information, enhance the detection signal-to-noise ratio, improve the detection ability of internal defects, suppress the change of surface emissivity, and realize the tomographic imaging of the inspected object. The method and system can be applied to non-destructive testing of equipment, material characterization evaluation, product quality control and structural health monitoring in the fields of aerospace, new materials, petrochemicals, nuclear power, railways, automobiles, special equipment, machinery, metallurgy, and civil engineering.

Description

Technical field [0001] The invention belongs to the technical fields of equipment non-destructive testing, material characterization evaluation, structural health monitoring and product quality control, and particularly relates to an eddy current thermal imaging detection method and system. Background technique [0002] With the development of modern science and industrial technology, non-destructive testing technology has become a necessary means to ensure product quality and equipment operation safety. The current representative non-destructive testing technologies mainly include radiographic testing, ultrasonic testing, penetrant testing, magnetic particle testing, eddy current testing and thermal imaging testing. [0003] Thermal imaging detection technology uses a heat source to heat the inspected object, uses a thermal imager to observe and record the temperature change information on the surface of the inspected object, and analyzes the changing temperature through thermal w...

AI Technical Summary

Problems solved by technology

[0006] At present, the eddy current thermal imaging detection technology has the following deficiencies: 1) The temperature signal decays rapidly with the increase of the detection depth, the signal-to-noise ratio decreases, and the detection effect on internal defects is poor; 2) It is impossible to achieve tomographic imaging of the object to be inspected; 3) The change of emissivity on the surface of the inspected object affects the effect of defect detection

However, none of the existing patents and literatures involve eddy current thermography defect detection and tomography methods and systems using cross-correlation algorithms

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