简介:Withtheadventofleft-handedmagneticmaterials,itisdesirabletodevelophigh-performancewavedevicesbasedontheirnovelpropertiesofwavepropagation.Thisletterreportsthespecialpropertiesofelasticwavepropagationinmagnetoelasticmultilayeredcompositeswithnegativepermeabilityascomparecdtothoseincounterpartstructureswithpositlvepermeability.Thesenovelpropertiesofelasticwavesarediscernedfromthediversifieddispersioncurves,whichrepresentthepropagationandattenuationcharacteristicsofelasticwaves.Tocomputethesedispersioncurves,themethodofreverberation-raymatrixisextendedfortheanalysisofelasticwavesinmagnctoelasticmultilayeredcomposites.Althoughonlytheresultsofasinglepiezomagneticandabinarymagnetoelasticlayerswithmechanicallyfreeandmagneticallyshortsurfacesaswellaspelrfectinterfaceareillustratedinthenumericalexamples,theanalysisisapplicablelomagnetoelasticmultilayeredstructureswithotherkindsofboundaries/interfaces.
简介:Weinvestigatetheinteractionbetweenapositivemassandanegativeeffectivemassthroughathreemasschainconnectedwithelasticsprings,apairofmassesisdesignedtohaveaneffectivenegativemass,anditinteractswiththethirdpositiveoneasifanequivalenttwo-masschain.Thedynamicsoftheequivalenttwo-masschainshowsthatthetwobodiesmaybeself-acceleratedinsamedirectionwhentheeffectivemassbecomesnegative,theexperimentisalsoconductedtodemonstratethistypeofmotion.Wefurthershowthattheenergyprinciple(Hamilton’sprinciple)isapplicableiftheenergyofthenegativemassunitisproperlycharacterized.Theresultmayberelevanttocompositewithcellsofeffectivenegativemass,theirinteractionwithmatrixmayleadtomorericherunexpectedmacroscopicresponses.