Abstract: A device and a method for testing a steel defect based on internal and external magnetic perturbation. The device includes: a magnetizer comprising a magnetization source and a magnet yoke, arranged on a surface of a sample, and configured to generate two types of typical magnetic field regions applied to testing based on internal and external magnetic perturbation; a double-row magnetic sensor probe, configured to collect internal and external magnetic perturbation data; a master controller, configured to perform pre-processing on the internal and external magnetic perturbation data, and store the pre-processed data; scanner wheels, configured to generate a sampling trigger pulse during scanning to enable the master controller to receive the internal and external magnetic perturbation data from the probes; and a host computer, configured to analyze the pre-processed data uploaded by the master controller to obtain a defect quantitative result.

Abstract: The present disclosure provides a device and a method for testing a steel defect based on internal and external magnetic perturbation. The device includes: a magnetizer comprising a magnetization source and a magnet yoke, arranged on a surface of a sample, and configured to generate two types of typical magnetic field regions applied to testing based on internal and external magnetic perturbation; a double-row magnetic sensor probe, configured to collect internal and external magnetic perturbation data; a master controller, configured to perform pre-processing on the internal and external magnetic perturbation data, and store the pre-processed data; scanner wheels, configured to generate a sampling trigger pulse during scanning to enable the master controller to receive the internal and external magnetic perturbation data from the probes; and a host computer, configured to analyze the pre-processed data uploaded by the master controller to obtain a defect quantitative result.

Abstract: Disclosed are a method and device for compressing and reconstructing data. The method includes: disposing a transmitting EMAT array and a receiving EMAT array; exciting a Lamb wave, receiving the Lamb wave, subjecting the Lamb wave to narrowband filtering with the narrowband frequency, to form detecting data x(n); analysing the detecting data with a DFT; reconstructing original detecting data and calculating a reconstruction error according to the measurement vector and the recovery matrix by using a TLBO algorithm; optimizing measurement vector and recovery matrix; transmitting the measurement vector to a supervisory device.

Abstract: A method for identifying a defect opening profile includes: acquiring a vertical component of a magnetic flux leakage signal of a defect; identifying right-angle features and corresponding right-angle position points of the defect from the vertical component; obtaining all possible right-angle types at each right-angle position point of the defect according to the corresponding right-angle feature of the vertical component; traversing all the possible right-angle types at each right-angle position point to determine respective optimal right-angle type at each right-angle position point; and drawing the defect opening profile according to the respective optimal right-angle type at each right-angle position point.

Abstract: A method for detecting a defect of a metal plate includes selecting N controllable emitting electromagnetic acoustic transducers EMATs as excitation transducers, and selecting M omnidirectionally receiving EMATs as receiving transducers, exciting an ultrasonic guided wave in a metal plate by a nth controllable emitting EMAT with a predetermined emission angle; determining whether each of M1 omnidirectionally receiving EMATs and the nth controllable emitting EMAT form a scattering group; for the scattering group, solving a position of a scattering point and a direction of a scattering side according to a distance between Tn and Rml, the emission angle and a travel time of the ultrasonic guided wave; performing a curve fitting on all the scattering points in directions of respective scattering sides to obtain a contour image of the defect.

Abstract: A method for identifying a defect opening profile includes: acquiring a vertical component of a magnetic flux leakage signal of a defect; identifying right-angle features and corresponding right-angle position points of the defect from the vertical component; obtaining all possible right-angle types at each right-angle position point of the defect according to the corresponding right-angle feature of the vertical component; traversing all the possible right-angle types at each right-angle position point to determine respective optimal right-angle type at each right-angle position point; and drawing the defect opening profile according to the respective optimal right-angle type at each right-angle position point.

Abstract: The method for calculating an MFL signal of a defect includes: determining sizes l0, w0 and d0 of an element defect according to sizes l, w and d of a target defect, acquiring an MFL signal HE (x, y, z) of the element defect; subjecting the MFL signal HE(x, y, z) to a three-dimensional Fourier transformation to acquire a frequency domain signal FE(?, ?, ?); subjecting the FE(?, ?, ?) to a translation transformation in the magnetization direction to acquire two frequency domain signals FE??(?, ?, ?) and FE?+(?, ?, ?); combining the FE??(?, ?, ?) and FE?+(?, ?, ?) to acquire a combined frequency domain signal FEcombine(?, ?, ?); subjecting the combined frequency domain signal FEcombine(?, ?, ?) to a three-dimensional inverse Fourier transformation to acquire an MFL signal HT(x, y, z) of the target defect.

Abstract: A method for detecting a defect of a metal plate includes selecting N controllable emitting electromagnetic acoustic transducers EMATs as excitation transducers, and selecting M omnidirectionally receiving EMATs as receiving transducers, exciting an ultrasonic guided wave in a metal plate by a nth controllable emitting EMAT with a predetermined emission angle; determining whether each of M1 omnidirectionally receiving EMATs and the nth controllable emitting EMAT form a scattering group; for the scattering group, solving a position of a scattering point and a direction of a scattering side according to a distance between Tn and Rm1, the emission angle and a travel time of the ultrasonic guided wave; performing a curve fitting on all the scattering points in directions of respective scattering sides to obtain a contour image of the defect.

Abstract: Disclosed are a method and device for compressing and reconstructing data. The method includes: disposing a transmitting EMAT array and a receiving EMAT array; exciting a Lamb wave, receiving the Lamb wave, subjecting the Lamb wave to narrowband filtering with the narrowband frequency, to form detecting data x(n); analysing the detecting data with a DFT; reconstructing original detecting data and calculating a reconstruction error according to the measurement vector and the recovery matrix by using a TLBO algorithm; optimizing measurement vector and recovery matrix; transmitting the measurement vector to a supervisory device.