| The quality problems of industrial products are very important.Timely detection and identification of crack and defect locations generated by industrial product parts can reduce the occurrence of accidents and ensure human safety.Eddy current testing can effectively detect cracks and defects in conductive material components,improving the reliability of mechanical products.The existing research on eddy current sensors has ignored the research on crack orientation identification.If the orientation information of cracks can be obtained based on the ability of eddy current sensors to determine whether there are cracks,it will provide great help for metal crack detection.In this paper,through the innovation of the detection coil of the cross rotating excitation sensor,a diagonal dislocation planar rotating field eddy current sensor and a four quadrant dislocation planar rotating eddy current sensor are designed,and the performance of the sensor is verified by simulation;A matching eddy current testing experimental system was constructed;The functions of the sensor and experimental system were experimentally verified.The main research work of this article is as follows:(1)The research on the theoretical basis of eddy current testing technology starts from Maxwell’s equations and analyzes the detection principle of cross structure rotating excitation.Through the relationship between rotating eddy current field excitation and cracks,it lays a theoretical foundation for the subsequent innovation of cross rotating excitation sensor detection coil and the design of a new cross rotating excitation planar eddy current sensor.(2)A diagonal dislocation planar rotating eddy current sensor and a four quadrant dislocation planar rotating eddy current sensor are designed.The design idea and design scheme of the sensor are introduced.A finite element simulation model is established for the two sensors based on Maxwell’s equation.Based on the finite element analysis results,the detection ability of the two new sensors for cracks in different directions is analyzed,and the sensitive direction of each detection coil in the two sensors to cracks is determined,According to the different signal timing picked up by different detection coils,the ability of two new sensors to identify the orientation of cracks is analyzed to determine the approximate orientation of cracks.(3)The construction of the eddy current testing experimental system has been completed.In order to efficiently conduct experimental research on crack detection,a three-dimensional scanning table system controlled by a computer numerical control system that can move along three coordinate axes was designed,and the selection,installation,and debugging of key components of the scanning table were completed;An experimental instrument platform for eddy current testing was constructed;A high gain multifunctional signal conditioning circuit board with dual channel detection signal input has been developed,and its design process and main functions are described.(4)Experimental verification and comparative study were conducted on the two new sensors designed.Through eddy current scanning experiments on cracks in different directions on aluminum plates,the crack detection capabilities of the diagonal dislocation type planar rotating eddy current sensor and the four quadrant dislocation type planar rotating eddy current sensor were verified;By comparing and analyzing the testing results with existing dual sector rotating field eddy current sensors and four quadrant rotating field eddy current sensors,it is proved that the two new sensors designed have the ability to identify the crack orientation. |
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