Design And Experimental Study Of Electromagnetic Ultrasonic System For Aluminum Plate Inspection

Aluminum plates are widely used in modern industry.But in the process of manufacture,transportation and later use of the sheet,the sheet will have various defects such as hole and corrosion due to the effect of external forces.Therefore,the quality of the sheet needs to be strictly tested.The commonly used non-destructive testing methods include ultrasonic testing,ray testing,eddy current testing and so on.Compared with other testing methods,electromagnetic ultrasonic testing has the advantages of non-contact,non-coupling,suitable for high temperature and speed detection and so on,so this paper uses electromagnetic ultrasonic technology to detect aluminum plates,designs and optimizes the electromagnetic ultrasonic testing system.Firstly,the characteristics of Lamb wave and the working principle of electromagnetic acoustic transducer applied to aluminum plate detection are studied in detail,and the structure of electromagnetic acoustic transducer is designed.The structure is verified by finite element simulation.Secondly,aiming at the shortcomings of the application of electromagnetic ultrasonic technology in detection,this paper optimizes the design of the electromagnetic ultrasonic system.The finite element method is used to get the coil parameters,then the impedance matching principle is analyzed and solved by combining the Smith circle diagram.According to the actual needs,an impedance matching circuit which can switch between multiple matching values and an ultra-wideband band-pass filter circuit with adjustable bandwidth and high selectivity are designed.Then,simulations and tests are designed to verify the correctness of each part of the circuit.Finally,the designed modules are used to construct a complete electromagnetic ultrasonic testing system,which is applied to the aluminum plate testing.The system performance testing experiment,defect identification experiment and excitation experiment at different frequencies are carried out to verify the feasibility and effectiveness of the optimization design of the electromagnetic ultrasonic system in this paper.