过控专业论文翻译英文版

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1、FATIGUECRACKINGOFTITANIUMTUBESINANINDUSTRIALHEATEXCHANGERABSTRACTThefatiguefractureofcommerciallypure(cp)titaniumtubesatrelativelylowtemperatures[120℃(250℉)]inashell-and-tubeheatexchangerwasstudied.Thecptitaniumtubesweresubjectedtoflow-inducedvibrationandco

2、mpressionaxialloadinginservice.Thecombinedstressesresultedinnumerousintergranularcracksincircumferentialdirection.Somecracksreachedasizethatresultedincompleteruptureoftubes.Fractographicanalysesindicatedthatthefracturewascausedbyhigh-cyclefatigue.Alargeport

3、ionofthetubewallindicatedalackofcharacteristicductilityofcptitanium.Thereducedductilitywasaresultofsecondphaseparticleinclusionandhydrogenabsorptionintubematerial.Thesecond-phaseparticlesprovidedeasysitesforinitiationandcoalescenceofmicrovoids.Hydrogenabsor

4、ptionoftitaniumresultedinanincreaseinhydridecontentandthusadecreaseinductility.INTRODUCTIONOneoftheproblemsheatexchangerdesignershavetofaceisthevibrationandsubsequentdamageoftubes,baffleplates,ortubesheets.Sincetubesaremoreflexible,theirdamageismorecommonly

5、countered.Astheshell-sidefluidflowspastthetubesatalargeflowrate,thetubesvibrateattheirnaturalfrequencieswhentheflowvelocitybecomessufficientlylarge[1].Increasedflowvelocityis,inpractice,intendedinheatexchangerstoimproveheattransferandtoreducebuildupofundesi

6、rablecondensateontubesurfaces.Thefrequencyoftubevibrationdependsprimarilyontubecross-sectionalgeometry,meansofsupport,andtubematerial.Sincenaturalfrequencyvariesasthereciprocaloftubelengthsquared,betweentworigidsupports,thefrequencycanbeincreasedwithmoreint

7、ermediatesupportsbytransversebafflesorsupportplatesalongthelength.Inmanyconstructions,thetubesarenotallsupportedatthesamesupportplatesorbaffles.Therefore,aspectrumofvibrationfrequenciesisexpected.Astheflowvelocityvaries,tubesvibrateatdiscretefrequencies.Inr

8、ecentyears,reactivematerialshavebeenwidelyadoptedinindustrialprocessingequipmentwherethematerialofconstructionmustbehighlyresistanttocorrosion.Titaniumofcommercialpuritywithexcellentcorrosionresistance