简介：

简介：ItisdifficulttodesignaplatewithwideattenuationzonesinlowfrequencyregionbasedonBraggscatteringmechanism.Aplatewithperiodicrhombusholesisoptimizedanddesigned.Basedonthefiniteelementmethodunderperiodicboundaryconditions,thein-planedispersioncurvesofperiodicallyperforatedplatearecalculatedviaCOMSOL.ThefrequencyresponsesofperiodicallyperforatedplateareinvestigatedviaANSYSsimulation.Theplateswithperiodicholesaresuspendedanddynamicallytestedundersinusoidalexcitations.Theresultsshowthataperiodicallyperforatedplatewithrhombusholeshaswiderattenuationzonesthanplateswithcircularandhexagonalholes.Materialpropertieshaveagreatinfluenceonattenuationzones:nitrile-butadienerubberandsiliconrubbercaneasilyobtainlow-frequencyzones,whileincreasingporositycreateslowerandwiderzones.Thewidthofattenuationzoneincreasesasthehorizontalangleoftherhombusholesincreases.Ananalysisoftheattenuationzones'generationmechanismshowsthattheplatewithperiodicholesexhibitscharacteristicsofBraggscatteringandlocalresonantphononiccrystal,indicatinganinherentrelationshipbetweentwotypesofmechanisms.Theoptimizedplatehasacompleteattenuationzonerangingfrom5281.76-8824.30Hz.Thevibrationsaresignificantlyreducedwhenthenumberofperiodsisnolessthantwo.Theattenuationrangeobtainedviathenumericalmethodisgenerallyconsistentwiththeexperiment.Theresearchshedslightonthenoiseinsulationplateandhasthepotentialtoimprovethesoundenvironmentinvariousapplicationsduetoitssimplemanufacturing.

简介：Choosingparticularsolutionsourceanditspositionhavegreatinfluenceonaccuracyofsoundfieldpredictionindistributedsourceboundarypointmethod.Anoptimizationmethodfordeterminingthepositionofparticularsolutionsourcesisproposedtogethighaccuracypredictionresult.Inthismethod,tripoleischosenastheparticularsolution.Theupperlimitfrequencyofcalculationispredictedbysetting1%volumevelocityrelativeerrorlimitusingvibrationvelocityofstructuresurface.Then,theoptimalpositionofparticularsolutionsources,inwhichtherelativeerrorofvolumevelocityisminimum,isdeterminedwithintherangeofupperlimitfrequencybysearchingalgorithmusingvolumevelocitymatching.Thetransfermatrixbetweenpressureandsurfacevolumevelocityisconstructedintheoptimalposition.Afterthat,thesoundradiationofstructureiscalculatedbythematrix.Theresultsofnumericalsimulationshowthatthecalculationerrorissignificantlyreducedbytheproposedmethod.Whentherearevibrationvelocitymeasurementerrors,thecalculationerrorscanbecontrolledwithin5%bythemethod.