Research On Pipeline Defects Detection And Liquid Viscosity Measurement Based On Innovative Magnetostrictive Transducers

Magnetostrictive guided wave detection technology can realize long distancedetection of specimen like pipe or rod, and it has been applied in engineering project.but the technology is mainly used to take fast scanning and positioning.However, it isdifficult to check the damage degree of characterization, application in complicatedstructure detection like pipeline with concrete coating is also reported less. This ismainly due to the following two aspects:(1) the ultrasonic guided wave andenvironmental medium (concrete covering layer, moisture, viscosity of liquid and soon), and the interaction mechanism of defects is not clear;(2) the development ofnew, high performance magnetostrictive sensor.Compared with longitudinal mode, torsional mode has the characteristics of nondispersion, more slowly in the low frequency range, especially suitable for defectdetection of short pipe; the torsional mode guided waves is also sensitive to the liquidviscosity. In this paper, pipe with concrete coated defect detection and Newton liquidviscosity measuring are two typical application, focus on the development of two newtype torsional mode magnetostrictive sensor, to solve quantitative wall pipeline defectdetection and the circumferential position respectively, as well as in small diameter(diameter as small as2mm) metal probe excitation and reception of T (0,1) modeguided wave problems. On this basis, using the new sensor, study on the T (0,1)mode in the external medium (concrete covering layer, viscous liquid) propagationcharacteristics, the detection performance under the influence of the corrosiondefects and the viscosity coefficient of liquid, the main research contents include:(1) develop torsional mode magnetostrictive sensor which is suitable for smalldiameter metal probe. Combined with the magnetic field finite element simulation andexperiment testing method, study on the effect of excitation properties of sensorwithdifferent iron cobalt alloy strip shape and pasting mode, preset making a sensoron3.5mm diameter metal rod, can produce (T0,1) mode guided wave, which is toform a sensor for measuring viscosity of liquid.(2) experimental study on measurement of the Newtonian liquid viscositycoefficient based on a metal rod. In the analysis of T (0,1) mode energy attenuationcoefficient in different frequency and the metal rod material, liquid viscositycoefficient, combining the analysis of experimental error sources, the metal rodsensor and test parameters were optimized. The sensor is used to measure theviscosity of glycerol, to verify the accuracy of the measurement method and test theperformance of new sensor to the viscosity measurement.(3) the development of the broadband, circular array tosional mode sensor.Based on the theory of Wiedeman effect, proposes a new static, dynamic magnetic field excitation and coupling, and designs a new circular array sensor. Check the newtype of circular array sensor for guided wave excitation efficiency, frequencycharacteristics and element consistency property, test results show that the new sensorhas the broadband characteristics which is different from traditional magnetostrictivesensors.(4) experimental study on multi-frequency guided wave detection of shortthrough-wall pipe. Use the broadband, circular array magnetostrictive sensor toproduce T (0,1) mode ultrasonic guided wave in short through-wall pipes,experimental study on the effect of T (0,1) mode guided wave propagationcharacteristics by concrete layer depth, as well as the ability of detecting concretecoated pipeline corrosion using T (0,1) mode; explore the multi-frequency guidedwave technology for size characterization of slot defect by using the broadbandsensor.