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1、AccelerationlevelsofdroppedobjectscmykAccelerationlevelsofdroppedobjectsIntroductionThispaperisintendedtoprovideanoverviewofdropThedropshockshocktesting,whichisdefinedastheaccelerationConsideranobjectdroppedontoahorizontalsurface.experiencedbyanobjectdroppedontoahardsurface.
2、Forthepurposeofthisevaluation,theobjectstartsThepracticalapplicationofthisworkistocharacterizeatrest,andfree-fallstoimpactarigidsurfaceaftertheaccelerationlevelsgeneratedwhenanaccelerometertravelingadistance,d,asshowninFigure1.After1isdroppedontoarigidsurface.Similardynamici
3、mpact,theobjectreboundsupwardtosomeheightd.2responsescanbeinferredtotheobjectonwhichtheaccelerometerismounted.Anaccelerometerisaparticularlyconvenientobjecttoevaluate,sinceitmaydirectlycharacterizetheamplitudeandpulsewidthgeneratedfromanimpact.Manyaccelerometershavemaximumac
4、celerationratingswhicharesufficienttomeasurehighaccelerationlevelsinawidevarietyofapplications.Itshouldberealizedd1thatinalmosteverycase,ratingsmaybeexceededbyseeminglybenignhandlingshocks.dSummary2Ithasbeendemonstratedthatwhendroppedfromaheightofonemeter,objectsmayimpactrig
5、idsurfaceswithverylargeaccelerations.Relativelyspeaking,lowermassobjectstendtoresultingreateraccelerations.AsFigure1anexample,anaccelerometer,withanormalmassofonly10grams,mayeasilybesubjectedto30000gwhenAnobjectinfree-fallexperiencesconstantaccelerationdroppedfromonemeteront
6、oarigidsteelplate.Iftheduetogravity,andthevelocityincreasesinthedownwardinterfaceonimpactisflat-to-flat,thelevelmayexceed80(negative)directionas000g.vt=gt(1)Theamountofaccelerationimpartedtoadroppedobjectisproportionaltothesquarerootofthedropheight,andThedistancetraveledisth
7、einverseofthepulsewidth.12dt=gt(2)2Thesetwoequationsmaybecombinedtodeterminethevelocityoftheobjectimmediatelypriortoimpact.v=–2gd(3)11Likewise,theupwardvelocityimmediatelyafterimpactisv=2gd(4)22Immediatelybeforeimpact,theobjectisstillinfree-fall.Iftheobjectwereapiezoelectric
8、accelerometer,itamaxwouldhavezerooutput.Thesameistrueimmediatelyafterimpact
