Development And Excitation Performance Test Of Giant Magnetostrictive Sensor Based On Terfenol-D With A Kind Of Knife

ith the development of the global economic society,pipeline transportation plays an indispensable role in the five modes of transportation,because of its large volume,good continuity,high safety factor and low cost.However,due to the long service life of the pipeline,and because of the environmental and human impact,the pipeline usually appears different degrees and forms of damage,including scratches,damage,corrosion and other defects.The damage of the pipeline will bring great waste of energy and economic loss,in more serious cases,it can cause personal injury and death,therefore,pipeline detection is particularly important.Conventional detection is mostly based on point-by-point.So the detection speed is slow,the detection distance is short and the efficiency is low.However,the ultrasonic guided wave detection technology has attracted more and more attention because of its long propagation distance,low attenuation and high detection efficiency.In the ultrasonic guided wave detection,the most commonly used sensor is the piezoelectric sensor,and the sensing element is PZT.The material limits the detection distance,due to the low coupling coefficient of the material and the poor energy conversion efficiency.Compared with PZT materials,the giant magnetostrictive material Terfenol-D has higher electromechanical coupling coefficient and energy conversion efficiency.So Terfenol-D is used as a sensitive element in this paper.Rectangular and cylindrical vibrating elements can not be coupled to the pipe,so the Terfenol-D is designed with a knife-like structure that can be coupled with arbitrary surface of the pipe.The internal components of the giant magnetostrictive sensor are designed in a combination of theoretical and experimental studies,and the influence of the main parameters of the sensor on the excitation effect is studied.The main research work and achievements of this paper include:1)In order to discuss the influence of the internal components of the sensor on the excitation signal,the experimental system of pipeline inspection is established,and theparameters of the sensor are experimentally studied by using the transmission line method to test the excitation performance of the giant magnetostrictive sensor.2)In order to make the Terfenol-D sensor can be applied to any surface of pipe,simulation software is used in this paper to analyze the vibration of knife type and cuboid structure Terfenol-D in loading the same signal.Due to the presence of other small vibration direction,this paper provides a kind of absorbing material,using theoretical calculation and experimental methods to analyze the influence of excitation signal with different position and thickness of backing layer.3)This paper researches two aspects of Terfenol-D sensor in excitation amplitude and signal-to-noise,and designs the bias magnetic field and driving coil.The influence of the parameters of the coil and the permanent magnet on the exciting signal is analyzed by experiment.The comparison of the excitation experiments between the giant magnetostrictive sensor based on Terfenol-D and the piezoelectric ceramic sensor is carried out.The amplitude,the echo coefficient and the positioning accuracy are compared.The gaint magnetostrictive Sensors based on a kind of knife developed in this paper have outstanding advantages.