Research And Test Analysis Of Defect Detection System Based On Alternating Current Field Measurement

Nondestructive testing bears the important task of quality assurance in industrial production,and the development of nondestructive testing technology determines the improvement of industrial product quality to a certain extent.Alternating current field measurement(ACFM)is a type of electromagnetic non-destructive testing,which can detect the surface or near surface defects of conductive metal workpieces.This method has a clear detection mechanism,is less affected by lift-off,and has a detection efficiency Higher advantages have received widespread attention in recent years.This article focuses on the ACFM technology,and mainly conducts specific research from the aspects of detection mechanism discussion,ACFM detection simulation analysis,detection test platform design and test analysis.First of all,ANSYS Maxwell simulation software was used to establish an AC electromagnetic field steel plate defect detection model,and the electromagnetic field distribution law of the workpiece surface was analyzed;the U-shaped magnetic core was used to enhance the electromagnetic field generated by the excitation coil on the workpiece surface;and various forms of defect surface magnetic induction strength were analyzed Distribution;establishing an AC electromagnetic field pipeline inspection model,exploring the differences between pipeline inspection and flat panel inspection,and exploring a curved surface inspection probe to detect pipeline circumferential defects.Then,use the related sensor design knowledge and electronic design technology to design and manufacture the AC electromagnetic field detection system test platform.With the miniature detection coil as the sensor and the control core based on the ATmega16 microcontroller,the DDS signal generation chip,instrumentation amplifier preamplifier circuit,power amplifier circuit,band-pass filter,RMS-DC circuit,communication circuit,power module And the programming design of the lower computer,after debugging,the detection test platform can complete the detection work normally,and the detection signal is stable.Finally,the use of built-in test platforms and various types of test blocks for experimental research on the application of AC electromagnetic fields: ACFM can detect defects in conductive metals such as 45 # steel,austenitic stainless steel,and aluminum;The method of magnetic core machining to adapt to the inspection pipeline can enhance the effect of ACFM technology on pipeline circumferential defect detection;the variation of defect length is closely related to the variation of Bz signal,and the variation of defect depth is related to the variation of Bx and Bz signal;When the detection scanning angle changes,the Bx signal can also present a magnetic flux leakage detection signal along with the change of the signal;this technology is less affected by lift-off.The lift-off height is 6mm,and the detection signal is still clearly identifiable.