離散元與有限元結合的多尺度計算方法及其應用.pdf

1、中國科學技術大學碩士學位論文離散元與有限元結合的多尺度計算方法及其應用姓名：胥建龍申請學位級別：碩士專業(yè)：固體力學指導教師：唐志平2003.6.1AbstractFiniteElementMethod(FEM)hasbeenallimportanttooltosolveengineeringproblemsandtomakescientificresearchessinceitsappearanceHoweverbecauseitisb

2、asedonthecontinuumsupposeitwillmeetsomedimcultieswhensolvingsomelocalnonuniformityproblems，DiscreteElementMethod(DEM)isanewnumericalconceptdevelopedtheseyears；itsagilitytosolveproblemsjsunmatchedButthehugecostconfinesits

3、moreapplicationCombiningthesetwomethodstoodecomputationalmodel，performingDEMatlocalscaleandperformingFEMatmacroscale，willdisplaytheadvantagesofthebothmethodsatthesanletimeBasedonreviewingtheintemationalrefcrencesonthemul

4、tiscalesimulation。aftercomparingtheequationsofthetwomethods，aconceptionoftransitionallayerissuggestedinthisdissertationtomakethesetwomethodscombinetogetherInthetransitionallayer，themechanicalparameterssuchasdisplacement，

5、strain，stress，andsoon，aretransferredsmoothlyMeanwhile，thecriticaltimeincrementsarediscussedatbothmethodsandauniformtimeincrementisdeterminedFirst，thetriangleplaneelementiscombinedwiththe3。DDEMThepropagationoftheelasticit

6、ywaveisusedtotestthismethod，andtheresultshowsthatthewavecallpropagatethetransitionallayersmoothly，sothismethodisfeasibleThen，thefailureofthepre—stressedAluminumplateunderthe1aserirradiationissimulatedusingthismulti—scale

7、method，performingDEMattheregionbeingclosedtothelaserandFEM鞋theregionfarfrom氌elaserThewholeprocessofthemicro—cracks’generating，developing，untiltheplate’sfailureisdisplayedclearlyandtheresultfittheexperimentquitewellThecra

8、ckproblemunderthedynamicloadingisalsoinvestigatedInthismodei，theregionnearthecracktipwherethestressisoddismeshedbytheDEMandtheotherregionismeshedbvFEMThecomputedJintegralshowsgoodconservationatdifferentintegrationregioni

9、nthissimulationanditisingoodagreementwiththeanalyticalsolutionThetriangleplateshellelementisalsotriedtocombinewiththe3DDEMtosimulatetheresponseofthecylindershellundertheinnerpressureFirst。thecylinderwiththesoleinnerpress

10、ureiscalculatedFindthatthemembranestressesinboththeFEMregionandDEMregionareingoodagreementwiththeanalyticalresultThenthelaserisimposedontheDEMregion，andthecylinderwithdifferentmmerialsissimulatedunderthiscoupledthermomee

11、hanicalloadTheresultshowsthatthreebasicfailuremodeexistsunderdifferentsituationsSomeeriticalvalueshaveheeftgotthroughthesimulationThecalculatedresultsfitexperimentaldataandtheothersimulationresultsquitewellKeyword：finite