文档名：高纯度横波蝶形线圈电磁超声换能器优化设计
摘要：蝶形线圈电磁超声换能器(EMAT)能够在铝块中同时激发出超声横波和纵波,接收信号中存在横波反射回波和纵波反射回波,纵波回波会影响缺陷检测的准确性.该文设计了一种变尺寸蝶形线圈EMAT,通过改变线圈不同位置导线的宽度与间距,改变不同位置的换能效率,以实现横波的增强和纵波的抑制.首先,考虑永磁体的空间磁场分布,分析蝶形线圈EMAT不同位置导线所受洛伦兹力与激发超声波类型的关系,结合有限元声场云图,得到EMAT接收信号中存在多个回波的原因;其次,研究线圈参数对换能效率和横波纵波幅值比的影响规律,利用有限元仿真确定变尺寸EMAT的设计参数;最后,制备常规与变尺寸蝶形线圈EMAT,采集无缺陷铝合金试块的回波,结果表明,当永磁体直径与线圈中心宽度比为1.92时,纵波幅值削弱了66.1%,横波幅值增大了36.3%,横纵波幅值比从5.8升至23.1.该文设计的变尺寸蝶形线圈EMAT实现了对纵波的削弱和横波的增强,提升了横波电磁超声内部缺陷检测的可靠性.
Abstract：Theelectromagneticacoustictransducers(EMATs)areelectromagneticallycoupledultrasonictransducerswhichcangenerateanddetectultrasonicwavesonelectricallyconductingmedia.Comparedwithspiralcoil,butterflycoilEMAThasthehighesteddycurrentandpressureatthecentralaxis,whichhassignificantadvantagesindetectionofinnerdefectsandthicknessmeasurement.ThebutterflycoilEMATiseasytogenerateshearwavesandlongitudinalwavesinanaluminumblock.Theechooflongitudinalwavewillbejudgedasadefectecho,whichbringsabigchallengetodefectidentification.Toimprovethedetectability,anoptimizationdesignmethodforhigh-purityshearwaveelectromagneticacoustictransducerwithbutterflycoilisprosed.Firstly,thespatialmagneticfielddistributionofthepermanentmagnetwastakenintoaccount,andtherelationshipbetweentheLorentzforceandthetypeofexcitationultrasonicwavesatdifferentpositionsofthebutterflycoilEMATwasanalyzed.Thepropagationcharacteristicsoftheultrasonicwaveswereexaminedina2Dfiniteelementsimulationmodel,andthecausesofmultipleechoeswereanalyzed.Theechoofthelongitudinalwavewillbejudgedasadefectecho,whichcanleadtoinaccuratedetectionresults.Secondly,abutterflycoilwithvariedsizewasproposed,wherethewirewidthandspacingofthebutterflycoilvarieswiththeposition,simultaneously,thetransductionefficiencywasaltered.Thelongitudinalwavesweresuppressedwhileshearwaveswereenhanced,andhigh-purityshearwaveswereachieved.Theinfluenceofbutterflycoilparametersontheexcitationefficiencyandtheamplitudesratioofshearandlongitudinalwavewasstudied,andtheoptimizedparametersweredeterminedthroughfiniteelementsimulation.Finally,theequal-sizeandvaried-sizebutterflycoilEMATwerepreparedforthecomparisonexperimentinvolvingshearwaveexcitationanddefectdetection.Theexperimentalresultsshowedthatwhenthemagnet-to-coilwidthratioreachedapproximately1.92,thelongitudinalwavewasweakenedby66.1%,whiletheshearwavewasenhancedby36.3%.Consequently,theshear-to-longitudinalamplituderatioincreasedfrom5.8to23.1.Aflatbottomedholewithadiameterof5mmwasinspectedusingtheoptimizationEMATtransducers,theamplitudeofthelongitudinalechoreflectedbythebottomandtheconvertedechohavebeensuppressed,andbothechoeswerealmostsubmergedinthenoisesignal.Theamplitudeoftheshearechoreflectedbytheflatbottomedholehasbeenenhanced,makingiteasiertodetectdefects.Thevaried-sizebutterflycoilEMATdesignedinthispapercanweakenthelongitudinalwaveandenhancetheshearwave,therebyimprovingthereliabilityofshearwaveelectromagneticultrasonicinternaldefectdetection.Thefollowingconclusionscanbedrawnfromtheanalysis:(1)ButterflycoilEMATiseasytogenerateshearwavesandlongitudinalwavesinanaluminumblock.Thereceivingsignalincludeechooflongitudinalwave,shearwaveandconvertedwave.Thelongitudinalwaveechowillbejudgedasadefectecho,whichbringsabigchallengetodefectidentification.(2)Reducingthewirewidthandspacingofthebutterflycoilinthemiddlepartcanimprovetheenergytransferefficiencyandenhancetheshearwaveamplitude,whileincreasingthewirewidthandspacingofthebutterflycoilinthesidepartcanweakentheenergytransferefficiencyandweakenthelongitudinalwaveamplitude.Theratioofshearwaveamplitudeandlongitudinalwaveamplitudevarieswiththemagnet-to-coilwidthratio.
作者：董明 李航辉 马宏伟 陈渊 曹现刚 Author：DongMing LiHanghui MaHongwei ChenYuan CaoXiangang
作者单位：西安科技大学机械工程学院西安710054;西安科技大学陕西省矿山机电装备智能检测与控制重点实验室西安710054西安科技大学机械工程学院西安710054西安科技大学陕西省矿山机电装备智能检测与控制重点实验室西安710054
刊名：电工技术学报 ISTICEIPKU
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(11)
分类号：TB552TM93
关键词：横波电磁超声换能器 高纯度横波 变尺寸蝶形线圈 缺陷检测
Keywords：Shearwaveelectromagneticacoustictransducers(EMATs) high-purityshearwave varied-sizebutterflycoil defectdetection
机标分类号：TG146.21O441TQ127.2
在线出版日期：2024年6月18日
基金项目：国家自然科学基金，国家自然科学基金，国家自然科学基金，陕西省自然科学基础研究计划-陕煤联合基金资助项目高纯度横波蝶形线圈电磁超声换能器优化设计[
期刊论文] 电工技术学报--2024, 39(11)董明 李航辉 马宏伟 陈渊 曹现刚蝶形线圈电磁超声换能器(EMAT)能够在铝块中同时激发出超声横波和纵波,接收信号中存在横波反射回波和纵波反射回波,纵波回波会影响缺陷检测的准确性.该文设计了一种变尺寸蝶形线圈EMAT,通过改变线圈不同位置导线的宽度...参考文献和引证文献
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高纯度横波蝶形线圈电磁超声换能器优化设计 Optimization Design of High-Purity Shear Wave Electromagnetic Acoustic Transducer with Butterfly Coil
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