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

Abstract

The invention discloses a cross-correlation eddy current thermal imaging defect detection and tomography method and a cross-correlation eddy current thermal imaging defect detection system. The system can work in the pulse mode, phase-lock mode, frequency modulating mode, phase modulating mode and other modes to generate different modulation signals, a high-frequency AC signal is modulated to generate different excitation signals so as to realize induction heating of a detected object, and at the same time, the time-dependent temperature information on the surface of the detected object is recorded to serve as detection data. A specific signal is adopted or is generated to serve as a reference signal, and the detection data and the reference signal are subjected to cross-correlation algorithm to realize pulse compression so as to obtain matching information such as phase coincidence, orthogonality, amplitude value and phase position of the detection data and the reference signal at different moments. Characteristic values are extracted from the matching information, the detection signal-to-noise ratio is enhanced, the internal defect detection capability is improved, change of surface emissivity is inhibited, and tomography of the detected object is realized. The method and the system can be applied to equipment nondestructive detection, material representation evaluation, product quality control and structural health monitoring in the fields of aeronautics and astronautics, new materials, petrochemical engineering, nuclear power, railways, automobiles, special equipment, machinery, metallurgy, civil construction and the like.

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 in particular 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. At present, 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 object to be inspected, uses a thermal imager to observe and record the temperature change information on the surface of the object to be inspected, and analyzes the changed temperatur...

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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