课件文稿7周课.pptx

1.6Measurmentreliability可靠性durability耐久性acceptability可接受性momentofinertia转动惯量，惯性矩straingages应变计stress应力tensiletest拉力测试specimen样品、标本Cantilever悬臂apparatus仪器、装置align对齐;排整齐;校准logarithmicdecrement对数衰减

SeveralpurposesofmeasurementsThequantitiesThemathematicalmodelsthevibrationmotionofasystemmassdampingStiffnesscoefficientsknowledgeofthethedeviceallrequiremeasurementallrequireforanalyzing

Measurementsassociatedwithvibrationareusedforseveralpurposes.First,thequantitiesrequiredtoanalyzethevibrationmotionofasystemallrequiremeasurement.Themathematicalmodelsproposedinprevioussectionsallrequireknowledgeofthemass,damping,andstiffnesscoefficientsofthedeviceunderstudy.

TheseCoefficientscanbemeasuredInavarietyways

Vibrationmeasurementsverifyimprovearealsousedtoanalyticalmodels

Otherusesofvibrationtestingtechniquesreliabilitydurabilitysearchingfordamagetestingforacceptabilityincludevibrationparameters.intermsof

Inmanycases,InfactmassisarelativelyeasyquantitytomeasureHowever,themassmomentofinertiamayrequireadynamicmeasurement.Themassofanobjectordeviceissimplydeterminedbyusingascale.

AmethodofmeasuringthemassmomentofinertiaofanirregularlyshapedobjecttheobjectontheplatformoftheapparatusofFigure1.29theperiodofoscillationofthesystem,istoplacemeasurel

SuspensionwiresoflengthlDiskofknownmomentI0massm0andradiusr0Figure1.29,trifilar(三线）suspensionsystemformeasuringthemomentofinertiaofirregularlyshapedobjectsMeasuringthemomentofinertiaofirregularlyshapedobjectsl

Byusingthemethodsofsection1.4,itcanbeshownthatthemomentofinertiaofanobject,I，placedonthediskofFigure1.29withitsmasscenteraligned(对准）verticallywiththatofthediskisgiven.(1.68)Themomentofinertiaofaobject

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