外文原文-使用磁致伸缩传感器产生和探测扭转导波.pdf

1、Generating and detecting torsional guided waves using magnetostrictivesensors of crossed coilsYi-Gon Kima,Hong-Sik Moona,Kyung-Jo Parkb,n,Jeong-Ki LeecaDepartment of Electrical Engineering,Chonnam National University,San 96-1,Dundeok-dong,Yosu 550-749,Republic of KoreabDepartment of Mechanical Engin

2、eering,Chonnam National University,San 96-1,Dundeok-dong,Yosu 550-749,Republic of KoreacInnovation Center for Safety Diagnosis Technology of Heavy&Chemical Facilities,Chonnam National University,San 96-1,Dundeok-dong,Yosu 550-749,Republic of Koreaa r t i c l e i n f oArticle history:Received 9 Febru

3、ary 2010Received in revised form22 October 2010Accepted 17 November 2010Available online 27 November 2010Keywords:Crossed-coilsMagnetostrictive sensorTorsional wavesPipelinesa b s t r a c tIn this work,we propose a crossed-coil magnetostrictive sensor consisting of a solenoid coil,a toroidalcoil,and

4、aferromagneticpatchforgeneratinganddetectingtorsionalwavesforpipeinspection.Weshowthatthedirectionofthemagneticfieldoftheferromagneticpatchcanbecontrolledbyadjustingtheinputcurrenttothetoroidalcoil.Inaddition,itisfoundthattheamplitudesofthesignalsreflectedfromthepipeend using a crossed-coil sensor a

5、re much larger than those using pre-magnetization techniques,andexcitation energies are used to generate the torsional waves only.From results on pipes with multiplecircumferentialnotches,anydefectslargerindiameterthan three timesthepipethickness were detectedusing the crossed-coil magnetostrictive

6、sensor.&2010 Elsevier Ltd.All rights reserved.1.IntroductionThe corrosion of pipelines is a major problem for the oil,gas,andpetrochemical industries.General wall-thinning and localized pittingcorrosion can occur from both the inside and the outside of the pipewalls.A high proportion of pipes are in

7、sulated,hence even externaldefectscannotbedetectedbyconventionalnondestructiveevaluation(NDE)techniques such as ultrasonic,liquid penetrant,or magneticparticle testing without the expense of removing the insulation.An attractive alternative to point or single location measure-ment would be to excite

8、 guided waves that propagate along thepipe.They can be used to inspect pipes over a long range and canreduce inspection time due to their rapid speed 1.Considerabletheoretical and experimental research has been carried out todevelop methods using guided waves 24.Among the varioussensors used in the

9、generating and receiving of guided waves,efforts have been made in recent years to use magnetostrictivesensor(MsS)technologies in association with the inspection ofpipelines.ThesesensorsusemagnetostrictiveeffectswhichrefertoJoule and its inverse effects(i.e.,Villari effects)5.Kwun6proposedamethodtog

10、enerateanddetectguidedtorsionalwavesusingmagnetostrictiveeffects.AsshowninFig.1(a),anickelstrip(a kind of ferromagnetic patch)was attached on the pipe around itscircumferentialdirectionandanencirclingsolenoidcoilwasplacedoverthe patch.The patch was pre-magnetized to provide a bias magneticfield in t

11、he pipe under inspection using permanent magnets,and analternating current(AC)pulse was applied to the coil.The resulting ACmagnetic field(a changing magnetic field)produced torsional guidedwaves in an adjacent ferromagnetic material through magnetostrictiveeffects.However,unwanted waves,such as lon

12、gitudinal or flexuralwaves,can be generated in addition to torsional waves using thismethodifthemagnitudeofthepre-magnetizationinthepatchandtheintensity of the magnetic field in the coil is not appropriate.Recently,Park et al.7 suggested another method to generateguided waves.A nickel strip(ferromag

13、netic patch)was attached onthepipeat451tothecircumferentialdirectionasshowninFig.1(b)toavoid excitation of the unwanted waves regardless of the inputcurrentmagnitude.However,inthismethod,itisdifficulttoexactlyandsimplyattachtheferromagneticpatchattheinspectionarea.Vinogradov proposed a crossed-coil

14、magnetostrictive sensorcomposedofasolenoidandatoroidalcoiltosolvetheseproblems8.In this work,we develop an advanced crossed-coil magnetos-trictive sensor early proposed by Vinogradov,consisting of asolenoid and a toroidal coil instead of a permanent magnet.Weshow that the direction of the magnetic f

15、ield of the ferromagneticpatch can vary according to the bias current input to the toroidalcoil.Experiment were performed on the pipes with multiplecircumferential notches,and the resulting data that show theperformance of the proposed sensor are presented with a compar-ison with the MsS using perma

16、nent magnets.2.Crossed-coil magnetostrictive sensorFig.2 shows the configuration of a crossed-coil sensor designedto generate and detect guided torsional waves in pipes.The sensorContents lists available at ScienceDirectjournal homepage: International0963-8695/$-see front matter&2010 Elsevier Ltd.All rights reserved.doi:10.1016/j.ndteint.2010.11.006nCorresponding author.Tel.:+82 61 659 3221;fax:+82 61 659 3229.E-mail address:kjpark40chonnam.ac.kr(K.-J.Park).NDT&E International 44(2011)145151cons