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.