材料力学性能（mechanical properties of materials）

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1、材料力学性能（Mechanicalpropertiesofmaterials）1elasticdeformation:materialdeformationafterloading,unloadingthispartofthedeformationdisappeared,thematerialreturnedtotheoriginalstateofnature.2plasticdeformation:theadjacentpartofamicrostructurecausespermanentdisplacementwithoutcausingmat

2、erialtorupture.3elasticlimit:thestressofelasticdeformationisexcessivetotheelasticplasticdeformation(yielddeformation).4modulusofelasticity:engineeringiscalledthestiffnessofmaterialsandrepresentstheresistanceofmaterialstoelasticdeformation.Theessenceistoproducethestressrequiredf

3、or100%elasticdeformation.5:fastanelasticloadingorunloading,additionalmaterialsandpropertiesofelasticstrainwithtimeofthe.6internalfriction:thedeformationenergyabsorbedbymaterialisgreaterthanthatofunloadingwhenitisloaded,thatis,somedeformationworktimesabsorbmaterial,andtheworkabs

4、orbedinthispartiscalledinternalfrictionofmaterial.7toughness:theabilitytoabsorbplasticdeformationworkandfractureworkbeforefracture.8superplasticity:undercertainconditions,presentsaverylargeelongation(about1000%)withoutneckingandfracture.9dimple:microscopicfractureofmicroporeagg

5、regationfracture.10coefficientofstressstate:ratioofmaximumshearstresstonormalstressinmaterialsunderdifferentloadingconditions.11shearmodulus:theratiooftorquetoshearstrainduringtorsion.12notchsensitivity:theratiooftensilestrengthtotensilestrengthofnotchedspecimens.NSR13hardness:

6、acharacterizationofthedegreeofhardnessofmaterials.Theabilityofamaterialsurfacetoresistdeformationorruptureinacertainvolume.14stressfieldstrengthfactor:theparameterthatreflectsthestressfieldintensityatthecracktip.15fracturetoughness:whenthestressfieldstrengthfactorincreasestoacr

7、iticalvalue,thematerialwithcracksbreaksdown,andthecriticalvalueiscalledfracturetoughness.16lowstressbrittlefracture:whenthematerialhasmacrocracks,thebrittlefractureoccurswhenthestresslevelisnothighorevenlowerthantheyieldlimit.17creep:metalunderconstanttemperatureandconstantload

8、slowplasticdeformationphenomenon.18creeplimit:resistan