| Carbon fiber reinforced plastics(CFRP)have been widely used in practical engineering due to their excellent properties,so it is very important to detect their structural properties.Compared with other testing techniques,eddy current nondestructive testing method has the characteristics of no coupling agent,non-contact and no influence on testing materials,which has been paid attention by the academic and engineering circles.In recent years,more and more composite materials appear in people’s field of vision,and eddy current testing technology has gained considerable development.The detection object is not only limited to metal materials,but also involved in the detection of composites with weak conductivity.However,the traditional eddy current detection technology is slow in scanning speed,backward in detection mode,low in detection sensitivity and inaccurate,and the detection equipment is bulky,which often requires a lot of manpower and material resources when scanning in a large area.Therefore,we need to improve the scanning mode of the system to improve the scanning efficiency of the system.At the same time,the hardware structure of the system is improved and upgraded to realize the integration and miniaturization of the system,and improve the detection efficiency and accuracy of the system.This subject integrates a reciprocating high-frequency eddy current testing system,which realizes the rapid and efficient detection of common cracks,fiber breakage,delamination and other damages of weakly conductive CFRP.The movement of the displacement platform is controlled by the LabVIEW program of the upper computer to realize the reciprocating fast scanning of the probe to the measured conductor,and the hardware circuit of the lower computer is controlled to realize the signal generation,processing and acquisition,and the detection results are displayed and stored in real time.The highest detection frequency of the system can reach 20 MHz,the detection process is automatic,and the frequency can be adjusted flexibly.The detection accuracy is high,and the detection results are intuitive and easy to understand.The main research contents of this topic are as follows:(1)The scanning mode of the system is improved from the original one-way interlaced scanning to the present reciprocating progressive scanning,which makes full use of the back and forth scanning process of the system and greatly improves the detection efficiency of the system.(2)Analyze the image degradation process in the detection results of the improved system,and study the principles of Wiener filtering method,Regularization filtering method,LR iterative restoration and Blind deconvolution restoration method,complete the compilation and improvement of the above four algorithms,realize the best restoration of misplaced blurred images,and evaluate and analyze the restoration results.At the same time,the hybrid programming of LabVIEW and Matlab is used to realize the restoration of the misplaced image.(3)The complete reciprocating high frequency eddy current testing system software is designed with LabVIEW program,which mainly includes the upper computer to control the movement of the displacement platform,the lower computer to set the excitation signal,data acquisition,real-time display of the results and data storage.Finally,based on C,the external interrupt program for data acquisition of the lower computer is written to ensure the synchronous data acquisition of the system.(4)The lower computer circuit is tested and the test results are given.The integrated reciprocating high-frequency eddy current testing system is used to verify the damage experiment of CFRP,such as fiber distribution,crack damage,delamination damage,etc.The test results are in line with expectations,which verifies the feasibility and practicability of the system. |
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