| As “One Belt and One Road” strategy is giving sustainable energy to the economic growth,China's demand for energy is increasing.Due to that pipelines are the most important tool among the modern types of energy transportation,domestic pipeline construction mileage continues to increase,while pipelines are operating in the long term.There could be different degrees of damage during the operations;therefore,it is very important to research on the safety inspection of the pipeline.Ultrasonic guided wave non-destructive testing technology has strong advantages over traditional non-destructive testing techniques,among which guided wave transducer is an important part of ultrasonic guided wave non-destructive testing system.It should be noted that the transducer's advantages directly affect the accuracy of the detection results.Especially,sexual judgment,and GMM materials have a huge electromechanical coupling coefficient and energy conversion efficiency compared to traditional piezoelectric materials.Therefore,the development of giant magnetostrictive guided wave transducers is of great significance for improving detection efficiency,detection accuracy,and detection range.In this paper,how the internal components of the giant magnetostrictive guided waveguide transducer impact on the excitation and receiving performance of the transducer is studied based on the combination of theory and experiment.The input impedance of the transducer and the transducer are analyzed.The impedance matching problem was investigated experimentally.In addition,the excitation and receiving performance of the transducer was verified by the detection of the artificial analog defect as well as the comparison with the traditional piezoelectric ceramic transducer.The main contributions and research results of this article include:(1)A pipeline guided wave test detection system was established.The detection mode was determined based on the dispersion curve of the pipeline,and the performance evaluation parameters of the giant magnetostrictive guided wave transducer were formulated.The ANSYS software was utilized to numerically simulate the structural dimensions of the composite vibrator,and further,the influence of the U-shaped elastic base material on the excitation performance was studied through experiments.(2)The bias magnetic field and alternating magnetic field structure are designed,giving full discussion of the influences of the size,number,arrangement of permanent magnets,the number of alternating coil layers,wire diameter,and fill factor on the excitation and reception performance of the transducer through test methods.In order to reduce the residual vibration of the transducer and to suppress the small vibration caused by the different strain of the composite structure,a kind of shock absorber was tried in this paper.The influence of the material on the performance of the excitation was also studied through the combination of theoretical analysis and test.(3)According to the equivalent circuit of the giant magnetostrictive transducer,the calculation expression of the input impedance of the transducer is derived.The change law of the influence of the matching capacitance on the excitation performance of the transducer was studied with the test method,which provides the theoretical basis for the design of the built-in impedance matching device for the subsequent transducer.(4)The developed transducer is used to test the pipeline detection.Through the detection of artificial simulation defects,the excitation and receiving performance of the transducer was verified,and the axial positioning accuracy,echo amplitude,relative sensitivity,signal to noise ratio and detection blind area are analyzed.Compared with the traditional piezoceramic transducers,such as the axial positioning accuracy,echo amplitude,relative sensitivity and detection blind area,the performance of the transducer on the excitation and reception performance is higher than the traditional piezoelectric ceramic transducer. |
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