Design Of Electromagnetic Acoustic Phased Array Transducer For Plate Flaw Detection

Metal plate is an important industrial raw materials,which need to use non-destructive testing methods to ensure quality.Traditional piezoelectric ultrasonic technology is difficult to apply to high temperature,automation and other occasions due to the coupling agent.Electromagnetic acoustic transducer needs no coupling agent,but the conversion efficiency is low and the beam control capability is poor.Electromagnetic acoustic phased array transducer combined with electromagnetic acoustic transducer and phased array can not only compensate those weakness of the piezoelectric transducer,but also has a strong sound beam control capability.However,the current research on electromagnetic acoustic phased array transducer is not enough to guide the design of electromagnetic acoustic phased array transducer,and the lack of experimental platform of electromagnetic acoustic phased array further limits the development of electromagnetic acoustic phased array transducer.In view of the above problems,this paper will study the design of electromagnetic acoustic phased array transducer for plate defect detection.To make up the shortage of study on the theory of electromagnetic acoustic phased array transducer,which the acoustic field is not clear,a FE model is proposed.Based on the analysis of the principle of phased array and the principle of electromagnetic acoustic transducer,this method uses the analytic method and the FE method to solve the phased array acoustic field characteristics and the single element electromagnetic acoustic transducer sound field characteristics.Based on the characteristics of the two acoustic fields,the structure of electromagnetic acoustic phased array transducer is determined,and the 2-D FE model of time domain and frequency domain is established.The characteristics of acoustic field distribution are obtained.To solve the problem of the lack of the theoretical guidance on the design of array parameters of electromagnetic acoustic phased array transducer,the FE method is used to simulate the influence of acoustic field parameters of electromagnetic acoustic phased array.Based on the method of determining the acoustic field of the electromagnetic acoustic phased array,the influence of the element spacing,the element width and the number of elements on the excitation field of the phased array is simulated and the general design method of the electromagnetic acoustic phased array transducer is determined.This method can lay a good foundation for the practical application of electromagnetic acoustic phased array technology.To make up the shortage of experimental platform of electromagnetic acoustic phased array,an experimental platform of electromagnetic acoustic phased array was designed.Based on the characteristics of electromagnetic acoustic phased array technology,the overall scheme and key parameters of electromagnetic acoustic phased array experiment platform are determined.Eight-channel electromagnetic acoustic phased transmitting circuit is designed to realize high precision multi-channel phase-controlled delay transmission.Complete the eight-channel electromagnetic acoustic receive circuit,which can controllable amplify the signal.Then write the software to control the modules.The simulation model and the acoustic field of the elements parameters is verified by measuring the sound field.An electromagnetic acoustic phased array scanning platform was constructed.The fan-shaped scanning was performed on the bottom of the plate with the depth of 2mm,and the defect detection capability of the electromagnetic ultrasonic phased array was verified.