简介:Inordertoovercometheexistingdisadvantagesofofflinelasershockpeeningdetectionmethods,anonlinedetectionmethodbasedonacousticwavesignalsenergyisprovided.Duringthelasershockpeening,anacousticemissionsen-soratadefinedpositionisusedtocollecttheacousticwavesignalsthatpropagateintheair.Theacousticwavesignalissampled,stored,digitallyfilteredandanalyzedbytheonlinelasershockpeeningdetectionsystem.Thenthesystemgetstheacousticwavesignalenergytomeasurethequalityofthelasershockpeeningbyestablishingthecorrespondencebetweentheacousticwavesignalenergyandthelaserpulseenergy.ThesurfaceresidualstressesofthesamplesaremeasuredbyX-raystressanalysisinstrumenttoverifythereliability.Theresultsshowthatboththesurfaceresidualstressandacousticwavesignalenergyareincreasedwiththelaserpulseenergy,andtheirgrowthtrendsareconsistent.Finally,theempiricalformulabetweenthesurfaceresidualstressandtheacousticwavesignalenergyisestablishedbythecubicequationfitting,whichwillprovideatheoreticalbasisforthereal-timeonlinedetectionoflasershockpeening.
简介:Thetime-frequencyanalysisofthesignalacquiredbyasingleground-basedmicrophoneshowsatwo-dimensionalinterferencepatterninthetime-frequencyplane,whichiscausedbythetimedelayofthereceivedsignalemittedfromalowflyingaircraftviathedirectpathandtheground-re-flectedpath.Amodelisdevelopedforestimatingthemotionparametersofanaircraftflyingalongastraightlineataconstantheightandwithaconstantspeed.MonteCarlosimulationresultsandex-perimentalresultsarepresentedtovalidatethemodel,andanerroranalysisofthemodelispresentedtoverifytheeffectivenessoftheestimationschemeadvocated.