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1TrainingmaterialsUSTUTS培训材料1.BasicPrinciplesofUltrasonicTesting.超声波检测（UT）的基本原理UltrasonicTesting(UT)useshighfrequencysoundenergytoconductexaminationsandmakemeasurements.Ultrasonicinspectioncanbeusedforflawdetection/evaluation,dimensionalmeasurements,materialcharacterization,andmore.UT是用高频声音能量来检测和测量的。超声波检测能用于缺陷的检测和评估，尺寸的测量、材料的特性和其他。UltrasonicInspectionisaveryusefulandversatileNDTmethod.Someoftheadvantagesofultrasonicinspectionthatareoftencitedinclude:超声波检测是很好用并且多功能的NDT方法。下面是它的一些优点：•Itissensitivetobothsurfaceandsubsurfacediscontinuities.•对表面和亚表面的不连续性都很灵敏。•ThedepthofpenetrationforflawdetectionormeasurementissuperiortootherNDTmethods.•缺陷检测和测量的深度方面优于其他的检测方法。•Onlysingle-sidedaccessisneededwhenthepulse-echotechniqueisused.•当用回波技术时，只需要单边。•Itishighlyaccurateindeterminingreflectorpositionandestimatingsizeandshape.•确定检测缺陷位置和测量大小和形状时非常精确。•Minimalpartpreparationisrequired.•只需要非常小的样品。•Electronicequipmentprovidesinstantaneousresults.•电子设备可以提供瞬间结果。•Detailedimagescanbeproducedwithautomatedsystems.•可以自动产生详细的图像。•Ithasotheruses,suchasthicknessmeasurement,inadditiontoflawdetection.•其他功能，除了缺陷的检测还有厚度的测量等。2.WavePropagation.波的传播Ultrasonictestingisbasedontime-varyingdeformationsorvibrationsinmaterials,whichisgenerallyreferredtoasacoustics.Insolids,soundwavescanpropagateinfourprinciplemodesthatarebasedonthewaytheparticlesoscillate.Soundcanpropagateaslongitudinalwaves,shearwaves,surfacewaves,andinthinmaterialsasplatewaves.Longitudinalandshearwavesarethetwomodesofpropagationmostwidelyusedinultrasonictesting.超声波的检测是基于声波在物料上产生随时间的变化的变形和震动。在固体中，声波基于离子震荡有四种传播模式：即可以传播纵波、横波、表面波和薄板板波。纵波和横波是超声波探伤主要使用的两种模式。2Inlongitudinalwaves,theoscillationsoccurinthelongitudinaldirectionorthedirectionofwavepropagation.Sincecompressionalanddilationalforcesareactiveinthesewaves,theyarealsocalledpressureorcompressionalwaves.Theyarealsosometimescalleddensitywavesbecausetheirparticledensityfluctuatesastheymove.Compressionwavescanbegeneratedinliquids,aswellassolidsbecausetheenergytravelsthroughtheatomicstructurebyaseriesofcomparisonandexpansion(rarefaction)movements.在纵波中，震荡发生在纵向或波传播的方向，由于压缩和扩张力激活了这些波，它们也叫压力波或压缩波，有时也称密度波，因为当它们移动时，它们的离子密度也在波动。压缩波在液体和固体中可以被激发，因为能量是经过原子结构用一系列的压缩和扩张而传递的。Inthetransverseorshearwave,theparticlesoscillateatarightangleortransversetothedirectionofpropagation.Shearwavesrequireanacousticallysolidmaterialforeffectivepropagation,andtherefore,arenoteffectivelypropagatedinmaterialssuchasliquidsorgasses.Shearwavesarerelativelyweakwhencomparedtolongitudinalwaves.Infact,shearwavesareusuallygeneratedinmaterialsusingsomeoftheenergyfromlongitudinalwaves.在横波或剪切波中，离子震荡是沿直角度或垂直于传播方向进行的。剪切波的传播需要一种很好的声学传播材料，因此，它在液体或玻璃中是不能有效传播的。横波相对纵波较弱。实际上，在材料中横波的激发通常也是用纵波的能量实现的。33.ModesofSoundWavePropagation.声波的传播模式Insolids,moleculescansupportvibrationsinotherdirections,hence,anumberofdifferenttypesofsoundwavesarepossible.Wavescanbecharacterizedinspacebyoscillatorypatternsthatarecapableofmaintainingtheirshapeandpropagatinginastablemanner.Thepropagationofwavesisoftendescribedintermsofwhatarecalled“wavemodes.”在固体中，分子能支持在其它方向的震动，因此，声波的不同形式是可能的。波在太空传播的特性是维持原有的形状和以稳定的方式传播。波的传播经常用“波的模式”来描述。Asmentionedpreviously,longitudinalandtransverse(shear)wavesaremostoftenusedinultrasonicinspection.However,atsurfacesandinterfaces,varioustypesofellipticalorcomplexvibrationsoftheparticlesmakeotherwavespossible.SomeofthesewavemodessuchasRayleighandLambwavesarealsousefulforultrasonicinspection.如前所述，纵波和横波是最经常使用的在超声波检测中。然而，在表面和内表面，不规则的结构和复杂的离子运动也有产生其他波形的可能。像瑞利波和兰姆波在超声波检测中也是使用的。4Thetablebelowsummarizesmany,butnotall,ofthewavemodespossibleinsolids.下面表格中是一部分波的模式：WaveTypesinSolids固体内波形ParticleVibrations离子震荡方向Longitudinal纵波Paralleltowavedirection平行波的传播方向Transverse(Shear)横波Perpendiculartowavedirection垂直波的传播方向Surface-Rayleigh表面瑞利波Ellipticalorbit-symmetricalmode椭圆轨道-对称PlateWave–Lamb板波-兰姆波Componentperpendiculartosurface(extensionalwave)分量垂直于表面PlateWave–Love板波-拉乌波Paralleltoplanelayer,perpendiculartowavedirection平行于平面层，垂直于波的方向Stoneley(LeakyRayleighWaves)斯通利波（漏瑞利波）Waveguidedalonginterface波沿界面传播Sezawa波Antisymmetricmode反对称模式Surface(orRayleigh)wavestravelthesurfaceofarelativelythicksolidmaterialpenetratingtoadepthofonewavelength.Surfacewavescombinebothalongitudinalandtransversemotiontocreateanellipticorbitmotionasshownintheimageandanimationbelow.Themajoraxisoftheellipseisperpendiculartothesurfaceofthesolid.Asthedepthofanindividualatomfromthesurfaceincreasesthewidthofitsellipticalmotiondecreases.Surfacewavesaregeneratedwhenalongitudinalwaveintersectsasurfacenearthesecondcriticalangleandtheytravelatavelocitybetween.87and.95ofashearwave.Rayleighwavesareusefulbecausetheyareverysensitivetosurfacedefects(andothersurfacefeatures)andtheyfollowthesurfacearoundcurves.Becauseofthis,Rayleighwavescanbeusedtoinspectareasthatotherwavesmighthavedifficultyreaching.表面波（或瑞利波）是在相对厚的材料表面大约一个波长的深度传播的播。表面波既有横向也有纵向的椭圆形，如下图所示。椭圆的长轴垂直于固体的表面。当表面原子的深度增加时，其椭圆运动的宽度将减小。当一纵波相交于第二个临界角的表面并且以中间速度前进时表面波被激发。瑞利波是很有用的，因为他的对表面缺陷非常灵敏，并且它可以沿曲面传播。由于这些优点，瑞利波经常被用于其它波形检测较难检测的区域。Platewavesaresimilartosurfacewavesexcepttheycanonlybegeneratedinmaterialsafewwavel