简介：BeamresponsesunderanimpactNDTloadarestudiedusingtheFourierandLaplacetransforms.Numericalcomputationisperformedforaparametricstudyofbeamandloadparameters.Itisshownthatunderanimpactload,thetimedurationfordisplacementtovanishistentimeslongerthanthatforvelocityandacceleration.Themaximumresponseisachievedfirstinacceleration,followedbyvelocity,andfinallydisplacement,allofwhichoccurbeforetheimpactloadisremoved.Atthemomentthattheimpactloadisremovedfromthebeam,thereisadiscontinuityinthevelocityandaccelerationresponses,butnotindisplacementresponse.TheeffectofKandphonbeamresponseismuchlesssignificantthanthatofEIandC,whichhavesimilareffectonbeamresponse.AsEIincreases,peakvaluesofdisplacement,velocityandaccelerationresponsedecrease.TheeffectofKonbeamresponseonlybecomesappreciableaftertheimpactloadisremoved.WhilethepeakofdisplacementremainalmostunchangedasKincreases,thedisplacementresponsedecaystozerofasterforlargeKvaluesthanforsmallKvalues.

简介：Thepropagationofstresswavesinalarge-diameterpipepileforlowstraindynamictestingcannotbeexplainedproperlybytraditional1Dwavetheories.Anewcomputationalmodelisestablishedtoobtainawaveequationthatcandescribethedynamicresponseofalarge-diameterthin-walledpipepiletoatransientpointloadduringalowstrainintegritytest.Ananalyticalsolutioninthetimedomainisdeducedusingtheseparationofvariablesandvariationofconstantmethods.Thevalidityofthisnewsolutionisverifiedbyanexistinganalyticalsolutionunderfreeboundaryconditions.Theresultsofthistimedomainsolutionarealsocomparedwiththeresultsofafrequencydomainsolutionandfieldtestdata.Thecomparisonsindicatethatthenewsolutionagreeswellwiththeresultsofprevioussolutions.Parametricstudiesusingthenewsolutionwithreferencetoacasestudyarealsocarriedout.Theresultsshowthatthemodenumberaffectstheaccuracyofthedynamicresponse.Amodenumbergreaterthan10isrequiredtoenablethecalculateddynamicresponsestobeindependentofthemodenumber.Thedynamicresponseisalsogreatlyaffectedbysoilproperties.Thelargerthesideresistance,thesmallerthedisplacementresponseandthesmallerthereflectedvelocitywavecrest.Thedisplacementincreasesasthestresswavespropagatealongthepilewhenthepileshaftisfree.Theincidentwavesofdisplacementandvelocityresponsesofthepilearenotthesameamongdifferentpointsinthecircumferentialdirectiononthepiletop.However,thearrivaltimeandpeakvalueofthepiletipreflectedwavesarealmostthesameamongdifferentpointsonthepiletop.