材料壓縮時的力學(xué)性能Mechanicalpropertie

材料壓縮時的力學(xué)性能Mechanicalpropertiesofmaterialsduringcompression主講人：王雅君12目錄CONTENTS低碳鋼壓縮實驗鑄鐵壓縮實驗LowcarbonsteelcompressionexperimentCastIronCompressionExperiment機械設(shè)計基礎(chǔ)MechanicalDesign測定低碳鋼(Q235鋼)的強度性能指標:服強度。Measurethestrengthperformanceindexoflow-carbonsteel(Q235steel):clothingstrength.測定鑄鐵的強度性能指標:抗拉強Measurethestrengthperformanceindexoflow-carbonsteel(Q235steel):clothingstrength.。觀察、比較低碳鋼(Q235鋼)和鑄鐵兩種材料的力學(xué)性能、壓縮過程及破壞現(xiàn)象。Observeandcomparethemechanicalproperties,compressionprocess,andfailurephenomenaoflow-carbonsteel(Q235steel)andcastiron.1低碳鋼壓縮實驗LowcarbonsteelcompressionexperimentONE一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment1.設(shè)備和儀器Equipmentandinstruments微機控制電液伺服萬能材料試驗機Mainresearchobject:Straightrods-rodswithstraightaxes.一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment2.實驗條件experimentalcondition常溫(20℃)、靜載(緩慢地加載）Normaltemperature(20℃),staticload(slowlyloaded)3.壓縮標準試件CompressionstandardL0=10d0或L0=5d0一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment4.實驗步驟Procedure(1)測量試樣尺寸Measuresamplesize(2)開機。打開電源開關(guān);啟動計算機，打開試驗機控制軟件;按復(fù)位按扭使控制系統(tǒng)上電。Poweron.Turnonthepowerswitch;Startthecomputerandopenthecontrolsoftwareofthetestingmachine;Presstheresetbuttontopoweronthecontrolsystem.(3)試驗參數(shù)設(shè)置Experimentalparametersettings(4)裝夾試樣。試樣應(yīng)置于球形承墊中心籍球形承墊自動調(diào)節(jié)實現(xiàn)軸向受載。Clampthesample.Thespecimenshouldbeplacedatthecenterofthesphericalbearingpadtoachieveaxialloadingthroughautomaticadjustmentofthesphericalbearingpad.球形承墊Sphericalbearingpad一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment4.實驗步驟Procedure(5)開始壓縮實驗測試。實驗過程中觀察圖形和數(shù)據(jù)顯示窗口以及試樣破壞情況Startcompressionexperimenttesting.Observationofgraphicsanddatadisplaywindowsduringtheexperiment,aswellassampledamage(6)打印輸出實驗曲線Printoutexperimentalcurves(7)卸載并取出試樣。Unloadandremovethesample.(8)關(guān)機。退出試驗程序，關(guān)閉主機油源電源，關(guān)閉測控系統(tǒng)電源關(guān)閉計算機。Shutdown.Exitthetestprogram,turnoffthemainengineoilsourcepower,turnoffthemeasurementandcontrolsystempower,andturnoffthecomputer.一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment(1)彈性階段obElasticstageob①彈性變形:Elasticdeformation:比例極限σ?:材料在不偏離應(yīng)力與應(yīng)變正比關(guān)系(胡克定律)條件下所能承受的最大應(yīng)力Proportionallimitσ?:Themaximumstressthatamaterialcanwithstandwithoutdeviatingfromtheproportionalrelationshipbetweenstressandstrain(Hooke'slaw)彈性極限σ?:材料產(chǎn)生純彈性變形時的最大應(yīng)力值Elasticlimitσ?:Themaximumstressvalueatwhichthematerialundergoespureelasticdeformation②斜直線oa:Obliquelineoa:σ=EεE—彈性模量Obliquelineoa:低碳鋼壓縮應(yīng)力-應(yīng)變圖Lowcarbonsteelcompressionstress-straindiagram一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment(2)屈服階段bcYieldstagebc應(yīng)力不增加，應(yīng)變不斷增加。Thestressdoesnotincrease,butthestraincontinuestoincrease.屈服極限σs:試樣還繼續(xù)發(fā)生明顯變形的最小應(yīng)力Yieldlimitσs:Theminimumstressatwhichthespecimencontinuestoundergosignificantdeformation低碳鋼壓縮應(yīng)力-應(yīng)變圖Lowcarbonsteelcompressionstress-straindiagram一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment(3)cd一一試件壓扁CD-flatteningoftestpieces比例極限σp、彈性極限σe、屈服極限σs彈性模量E與拉伸時相同，而強度極限σb,測不出Proportionallimitσp.Elasticlimitσe.YieldlimitσsTheelasticmodulusEisthesameasintension,whilethestrengthlimitσb.Unabletomeasure低碳鋼壓縮應(yīng)力-應(yīng)變圖Lowcarbonsteelcompressionstress-straindiagram一、低碳鋼壓縮實驗Lowcarbonsteelcompressionexperiment經(jīng)過屈服階段后，低碳鋼試樣被壓成鼓形Aftertheyieldstage,thelow-carbonsteelsampleispressedintoadrumshape繼續(xù)不斷加壓試樣將愈壓愈扁，壓成薄餅形狀而不破裂Continuetoapplypressurecontinuously,andthesamplewillbecomeflatterandflattened,formingathincakeshapewithoutbreaking低碳鋼壓縮的變形DeformationofLowCarbonSteelunderCompression2鑄鐵壓縮實驗CastIronCompressionExperimentTWO二、鑄鐵壓縮實驗CastIronCompressionExperiment

鑄鐵壓縮應(yīng)力-應(yīng)變圖Compressionstress-straindiagramofcastiron應(yīng)力割線Stresssecant二、鑄鐵壓縮實驗CastIronCompressionExperiment剪切破壞，鑄鐵試樣破裂后呈鼓形，破裂面與軸線大約成45°Shearfailure,thecastironsampleshowsadrumshapeafterfracture,andthefracturesurfaceisapproximately45°fromtheaxis.鑄鐵壓縮的變形Compressiondeformationofcastiron1自測題一單選題SelfTestQuestion1-MultipleChoiceQuestion1.脆性材料的失效形式為_________。Thefailureformofbrittlematerialsis_________.

A.屈服失效Yieldfailure

B.斷裂失效YieldfailureC.扭轉(zhuǎn)失效Torsionalfailure

D.點蝕失效TorsionalfailureBB自測題SELF-TEST2完成實驗報告，包括實驗?zāi)康?，設(shè)備名稱及型號，實驗原始數(shù)據(jù)記錄(列表表示)與實驗數(shù)據(jù)處理，試樣破壞形狀示意圖，分析討論。Completetheexperimentalreport,