24167.多晶鈹微觀彈性力學(xué)行為的數(shù)值分析

1、獨創(chuàng)性聲明本人聲明所呈交的論文是我個人在導(dǎo)師指導(dǎo)下進行的研究工作及取得的研究成果。盡我所知，除了文中特別加以標注和致謝的地方外，論文中不包含其他人已經(jīng)發(fā)表或撰寫過的研究成果，也不包含為獲得寧夏大學(xué)或其它教育機構(gòu)的學(xué)位或證書而使用過的材料。與我一同工作的同志對本研究所做的任何貢獻均已在論文中作了明確的說明并表示了謝意。研究生簽名：約翔時間：刀／尹年尹月7礦日關(guān)于論文使用授權(quán)的說明本人完全了解寧夏大學(xué)有關(guān)保留、使用學(xué)位論文的規(guī)定，即：學(xué)校有

2、權(quán)保留送交論文的復(fù)印件和磁盤，允許論文被查閱和借閱?？梢圆捎糜坝　⒖s印或掃描等復(fù)制手段保存、匯編學(xué)位論文。同意寧夏大學(xué)可以用不同方式在不同媒體上發(fā)表、傳播學(xué)位論文的全部或部分內(nèi)容。l保密的學(xué)位論文在解密后應(yīng)遵守此協(xié)議)研究生簽名：乃朔時間：歹∥壚年鄉(xiāng)月7pIEI導(dǎo)師簽名：／『叭多了時間：刪≯年夕月徊Abs仃actAsalowatomicnumberstructurematerialberylliumhasmanysuperiorphys

3、icalandmechanicalpropertiessuchaslowdensity，hi曲elasticmodulus，gooddimensionalstabilityandsuperiorthermalperformanceDuetothesesuperiorphysicalandmechanicalpropertiesberylliumhasawiderangeofapplicationsinthenuclearenergyin

4、dustry，weaponsystem，aerospaceindustryandotherfieldsBerylliumproducedbypowdermetallurgicalprocessisconsideredconstructedbysinglecrystalswhoseorientations，shapesandsizearedistributedrandomlyBecauseofrandomgrainorientationa

5、ndirregularshapepolycrystallineberylliumispronetoelasticmismatchwithinthegrainoratthegrainboundariesunderexternalloadMetalberylliumhasstrongbrittleness，andelasticmismatchinmaterialdefectinberylliumwillleadbrittlefracture

6、Therefore，weneedtoconsiderthemicrograinstructuresuchasgramgeometricalshapeanddistributionofgrainorientationInthispaperberylliumcrystallinemodelswereestablishedbasedonconsideringtherandomdistributionofgrainorientationandr

7、egularityofgrainshape，andnumericalanalysisonmicroelasticmismatchbehaviororstiffnesscoefficientwerecarriedonbyusingtheANSYSsoftwareAroundthisproblemthispapermainlyfinishedthefollowingwork：1Consideringtheinfluenceof咖shapeo

8、nthematerialelasticmismatchtheidealregularpolycrystallinemodelincludingsquarepolycrystallineorhexagonalpolycrystallinemodelandirregularpolycrystallinemodelbasedonVoronoidiagrammethodwereestablished2Forconsideringanisotro

9、picmechanicalpropertiesofthesinglecrystal，thecoordinatetransformationofelasticstiffnessmatrixcontainingfiveindependentparametersofthemonocrystalberylliumgrainwithhcpstructureWaScarriedoutandelaSticpropertyparametersofgra

10、inwithanyorientationwereobtainedAssigningthesecalculatedparameterstodifferentsrainsrandomlythentheaimofconsideringelasticpropertydifferencesundertheconditionofrandomdistributionsofgramorientationwereachieyed3Finiteelemen

11、tanalysisWascarriedoutonregularorirregularpolycrystallinemodeltostudytheinfluenceofgrmshapeonelasticmismatchinberyllium4AdoptingtheVoronoipolycrystallinemodel，theinfluenceofberylliumgrainstructureincludinggrainsize，礎(chǔ)boun

12、daryandcontentorsizeofberylliumoxideparticlesonmicroelaSticmismatchwerestudiedBasedontheaboveworkfiniteelementanalysisbyANSYSWascarriedoutonpolycrystallinemodelofmetalberylliumThecalculationsshowthatelasticmismatchinVoro

13、noipolycrystallinemodelismoresignificantthantheregularpolycrystallinemodelMismatchstressmainlyOCCLWSatthegrainboundaryanditisabout10％higherthantheaveragestressStressOnthegrainboundaryintoanormaldistribution；Asthegrainsiz

14、edecreaSe，theproportionofhi【ghstressareaorthematerialstiffnesscoefficientincreasesWithcontentofberylliumoxideatgrainboundaryincreasing，themaximumstressinandstiffnesscoefficientofmodelsincreasesgraduallyBerylliaparticlesi