振動(dòng)的定義和術(shù)語-畢業(yè)論文外文翻譯

1、外文翻譯外文翻譯題目振動(dòng)的定義和術(shù)語學(xué)生姓名專業(yè)名稱機(jī)械設(shè)計(jì)制造及其自動(dòng)化指導(dǎo)教師2016年5月10日教學(xué)單位機(jī)械工程學(xué)院disturbancese.g.shockimpactfcesrollingloadsoverbridgescarsdrivenoverpotholesi.e.fceswhichdonotrepeatatregularintervals.Althoughtransientsaretemparycomponentsof

2、vibrationalmotiontheycancauselargeamplitudesinitiallyconsequenthighstressbutinmanycasestheyareofshtdurationcanbeignedleavingonlysteadystatevibrationstobeconsidered.SteadyStateVibrationsareoftenassociatedwiththecontinuous

3、operationofmachineryalthoughperiodicarenotnecessarilyharmonicsinusoidal.Sincevibrationsrequireenergytoproducethemtheyreducetheefficiencyofmachinesmechanismsbecauseofdissipationofenergye.g.byfrictionconsequentheattransfer

4、tosurroundingssoundwavesnoisestresswavesthroughframesfoundationsetc.Thussteadystatevibrationsalwaysrequireacontinuousenergyinputtomaintainthem.RomVibrationisthetermusedfvibrationwhichisnotperiodici.e.hasnomadeclearsevera

5、lofwhichareprobablyknowntosciencestudentsalready.PeriodCycleFrequencyAmplitudeAsteadystatemechanicalvibrationisthemotionofasystemrepeatedafteranintervaloftimeknownastheperiod.Themotioncompletedinanyoneperiodoftimeiscalle

6、dacycle.Thenumberofcyclesperunitoftimeiscalledthefrequency.Themaximumdisplacementofanypartofthesystemfromitsstaticequilibriumpositionistheamplitudeofthevibrationofthatpartthetotaltravelbeingtwicetheamplitude.Thus“amplitu

7、de”isnotsynonymouswith“displacement”butisthemaximumvalueofthedisplacementfromthestaticequilibriumposition.NaturalFcedVibrationAnaturalvibrationoccurswithoutanyexternalfceexceptgravitynmallyariseswhenanelasticsystemisdisp

8、lacedfromapositionofstableequilibriumreleasedi.e.naturalvibrationoccursundertheactionofrestingfcesinherentinanelasticsystemnaturalfrequencyisapropertyofhesystem.Afcedvibrationtakesplaceundertheexcitationofanexternalfce(e