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  • 简介:StructurehealthmonitoringbasedondiagnosticLambwaveshasbeenfoundtobeoneofthemostpromisingtechniquesrecently.Thispaperhasabriefreviewofthenewdevelopmentsonthismethodincludingthebasicnovelofthemethod,fundamentalsandmathematicsofLambwavepropagation,narrowbandandwidebandLambwaveexcitationmethods,optimizationofexcitationfactorsanddiagnosticLambwaveinterpretationmethods.

  • 标签: A结构健康监测 无损检测 射线检验 兰姆播 SHM
  • 简介:LowfieldNMRtechniquewasappliedtoinvestigatethehydrationofcementpasteswithdifferentwatertocementratiosoradditionofsuperplasticizer.Asanondestructivemethod,thistechniquecanbeusedtomonitorthehydrationkineticsprocessbyfollowingthechangesoflongitudinalrelaxationtime(T1)ofwaterconstrainedinthepastes.TheexperimentalresultsindicatethattheT1distributionsofwaterinthefreshpastenormallyexhibitebimodaldistribution,wherethelargepeakiscorrespondingtothefreewaterwhilethesmalloneiscontributedbythewaterstoredintheflocculations.TimedependenceoftheweightedaverageT1hasagoodagreementwiththehydrationprocessandcouldbedividedintofourstages,ie,initialperiod,dormantperiod,acceleratedperiodandsteadyperiod.Thehydrationmechanismofeachstagewasdescribedbasedonthetheoryofcementchemistry.Inaddition,thetotalsignalintensity,whichisproportionaltothecontentofthephysicallyboundwaterinthesamples,decreasesuccessivelyduringthehydrationreflectingtheconsumptionofphysicallyboundwaterbyhydrationreactions.

  • 标签: 水化动力学 低场核磁共振 水泥浆体 现场监测 核磁共振技术 纵向弛豫时间
  • 简介:Liquidcompositemoulding(LCM)processesareusedtomanufacturehighqualityandcomplex-shapedcompositepartsintheautomotive,marine,aerospaceandcivilindustries.On-linesensingplaysanimportantroleincontrollingthequalityofthefinalproductintheLCMmanufacturingenvironment.Thelong-periodfibergrating(LPG)technology,anewreal-timefiberopticsensorsystem,wasdevelopedtomonitortheflowfrontprogression.Thesensoroperationandcharacterizationundervariousprocessconditionswerediscussedindetail.TheexperimentalresultsshowedthatLPGsensorswererobustandreliabletodetectthearrivalofresinatpre-selectedlocationsinstructureswithlow-mediumfibervolumefraction;howeverwerelimitedatdifferentdepthsinstructureswithhighfibervolumefraction.

  • 标签: 复合材料 液态成型 流量监测 长周期格子
  • 简介:Withtheaidofthelatestfiberopticsensingtechnology,parametersinthecureprocessofthermosettingresin-matrixcomposite,suchastemperature,viscosity,voidandresidualstress,canbemonitoredentirelyandefficiently.Inthispaper,experimentresultsofviscositymeasurementincompositecureprocessinautoclaveusingfiberopticsensorsarepresented.Basedonthesensedinformation,acomputerprogramisutilizedtocontrolthecureprocess.Withthistechnology,thecureprocessbecomesmoreapparentandcontrollable,whichwillgreatlyimprovethecuredproductsandreducethecost.

  • 标签: 光纤传感器 监控过程 高压灭菌器 残余压力