吉林大学材料科学基础.ppt

Chapter7MechanicalProperties 第七章力学性质 吉林大学材料科学与工程学院曹占义 2020 3 26 Chapter7MechanicalProperties 2 Mechanicalproperties Themechanicalbehaviorofamaterialreflectstherelationshipbetweenitsresponseordeformationtoanappliedloadorforce Importantmechanicalproperties strength hardness ductility stiffness 7 1INTRODUCTION 力学性质 2020 3 26 Chapter7MechanicalProperties 3 Waysthatloadapplied Tension CompressionSheartorsion 7 2CONCEPTSOFSTRESSANDSTRAIN 拉伸载荷 压缩载荷 剪切载荷 扭转载荷 2020 3 26 Chapter7MechanicalProperties 4 TENSIONTESTS 7 2CONCEPTSOFSTRESSANDSTRAIN 2020 3 26 Chapter7MechanicalProperties 5 COMPRESSIONTESTS SHEARANDTORSIONALTESTS 7 2CONCEPTSOFSTRESSANDSTRAIN 2020 3 26 Chapter7MechanicalProperties 6 GEOMETRICCONSIDERATIONSOFTHESTRESSSTATE 7 2CONCEPTSOFSTRESSANDSTRAIN 2020 3 26 Chapter7MechanicalProperties 7 Stress straindiagramandmodulusofelasticity 7 3STRESS STRAINBEHAVIOR 2020 3 26 Chapter7MechanicalProperties 8 Forceversusinteratomicseparationtoexplaintheelasticdeformation 7 3STRESS STRAINBEHAVIOR 2020 3 26 Chapter7MechanicalProperties 9 Elasticmodulusdependsonatomicbonding 7 3STRESS STRAINBEHAVIOR 2020 3 26 Chapter7MechanicalProperties 10 Shearstressandstrain 7 3STRESS STRAINBEHAVIORAND7 4ANELASTICITY 7 4ANELASTICITYAnelasticdeformation Time dependentelastic nonpermanent deformation 滞弹性 2020 3 26 Chapter7MechanicalProperties 11 Poisson sratio 7 5ELASTICPROPERTIESOFMATERIALS 2020 3 26 Chapter7MechanicalProperties 12 7 6TENSILEPROPERTIES YIELDINGANDYIELDSTRENGTH 2020 3 26 Chapter7MechanicalProperties 13 7 6TENSILEPROPERTIES TENSILESTRENGTH 2020 3 26 Chapter7MechanicalProperties 14 7 6TENSILEPROPERTIES DUCTILITY 塑性 延展性 2020 3 26 Chapter7MechanicalProperties 15 7 6TENSILEPROPERTIES Mechanicalbehaviorforironatthreetemperatures 2020 3 26 Chapter7MechanicalProperties 16 7 6TENSILEPROPERTIES RESILIENCE 回 弹性 弹性能 总应变能 2020 3 26 Chapter7MechanicalProperties 17 7 6TENSILEPROPERTIES 6 TOUGHNESS 强韧性 Forstaticsituation theareabelowthecurveof Fordynamic highstrainrate situation notchtoughnessfracturetoughness Fordynamic highstrainrate situation notchtoughness缺口冲击韧性fracturetoughness Fordynamic highstrainrate situation notchtoughness缺口冲击韧性fracturetoughness断裂韧性 2020 3 26 Chapter7MechanicalProperties 18 7 7TRUESTRESSANDSTRAIN TrueStress T 真实应力 TrueStrain T 真实应力和工程应力的关系 真实应变和工程应变的关系 2020 3 26 Chapter7MechanicalProperties 19 7 7TRUESTRESSANDSTRAIN TrueStress T 真实应力 2020 3 26 Chapter7MechanicalProperties 20 7 7TRUESTRESSANDSTRAIN TrueStress T 真实应力 2020 3 26 Chapter7MechanicalProperties 21 7 8ELASTICRECOVERYDURINGPLASTICDEFORMATION Unloadingcycles 2020 3 26 Chapter7MechanicalProperties 22 7 9COMPRESSIVE SHEAR ANDTORSIONALDEFORMATION COMPRESSIVEDEFORMATION SHEARDEFORMATION TORSIONALDEFORMATION 压缩变形 剪切变形 扭转变形 2020 3 26 Chapter7MechanicalProperties 23 MECHANICALBEHAVIOR CERAMICS 7 10FLEXURALSTRENGTH 陶瓷材料的 抗弯强度 2020 3 26 Chapter7MechanicalProperties 24 MECHANICALBEHAVIOR CERAMICS 7 11ELASTICBEHAVIOR 陶瓷材料的 弹性行为 2020 3 26 Chapter7MechanicalProperties 25 MECHANICALBEHAVIOR POLYMERS 7 13STRESS STRAINBEHAVIOR 高分子材料的 应力 应变行为 脆性高分子材料 塑性高分子材料 完全弹性高分子材料完全弹性体 人造橡胶 2020 3 26 Chapter7MechanicalProperties 26 MECHANICALBEHAVIOR POLYMERS 7 13STRESS STRAINBEHAVIOR Themechanicalcharacteristicsofpolymers forthemostpart arehighlysensitivetotherateofdeformation strainrate thetemperature andthechemicalnatureoftheenvironment thepresenceofwater oxygen organicsolvents etc 2020 3 26 Chapter7MechanicalProperties 27 MECHANICALBEHAVIOR POLYMERS 7 13STRESS STRAINBEHAVIOR 高分子材料的 应力 应变行为 屈服强度 抗张强度 2020 3 26 Chapter7MechanicalProperties 28 MECHANICALBEHAVIOR POLYMERS 7 13STRESS STRAINBEHAVIOR Themechanicalcharacteristicsofpolymers forthemostpart arehighlysensitivetotherateofdeformation strainrate thetemperature andthechemicalnatureoftheenvironment thepresenceofwater oxygen organicsolvents etc 材料 polymethylmethacrylate聚甲基丙烯酸甲酯 Ingeneral decreasingtherateofdeformationhasthesameinfluenceonthestress straincharacteristicsasincreasingthetemperature thatis thematerialbecomessofterandmoreductile 2020 3 26 Chapter7MechanicalProperties 29 MECHANICALBEHAVIOR POLYMERS 7 14MACROSCOPICDEFORMATION 高分子材料的 宏观变形 7 15VISCOELASTICITY粘弹性 高分子材料的特性 2020 3 26 Chapter7MechanicalProperties 30 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 7 16HARDNESS Hardness Themeasureofamaterial sresistancetodeformationbysurfaceindentationorbyabrasion 硬度 Mohsscale whichrangedfrom1onthesoftendfortalcto10 onthehardend fordiamond Measuredhardnessesareonlyrelative ThereasonsthatHardnesstestsareperformed 1 Theyaresimpleandinexpensive 2 Thetestisnondestructive 3 Othermechanicalpropertiesoftenmaybeestimatedfromhardnessdata 2020 3 26 Chapter7MechanicalProperties 31 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 硬度测量技术 Measuredhardnessesareonlyrelative 2020 3 26 Chapter7MechanicalProperties 32 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 硬度换算图 Measuredhardnessesareonlyrelative 2020 3 26 Chapter7MechanicalProperties 33 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 硬度与强度的关系 Measuredhardnessesareonlyrelative CORRELATIONBETWEENHARDNESSANDTENSILESTRENGTH 2020 3 26 Chapter7MechanicalProperties 34 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 硬度与抗拉强度的关系 Measuredhardnessesareonlyrelative CORRELATIONBETWEENHARDNESSANDTENSILESTRENGTH 2020 3 26 Chapter7MechanicalProperties 35 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 陶瓷材料的硬度 Measuredhardnessesareonlyrelative 7 17HARDNESSOFCERAMICMATERIALS 2020 3 26 Chapter7MechanicalProperties 36 HARDNESSANDOTHERMECHANICALPROPERTYCONSIDERATIONS 高分子材料的撕裂强度和硬度 Tearstrength themechanicalparameterthatismeasured istheenergyrequiredtotearapartacutspecimenthathasastandardgeometry 7 18TEARSTRENGTHANDHARDNESSOFPOLYMERS Polymersaresofterthanmetalsandceramics andmosthardnesstestsareconductedbypenetrationtechniquessimilartothosedescribedformetalsintheprevioussection Rockwelltestsarefrequentlyusedforpolymers 2020 3 26 Chapter7MechanicalProperties 37 PROPERTYVARIABILITYANDDESIGN SAFETYFACTORS 金属材料性能的可变性 数据分散性 ScatterandVariabilityofmaterialspropertiesareinevitableandmustbedealtwithappropriately 7 19VARIABILITYOFMATERIALPROPERTIES Question1 Whatisthefracturestrengthofthisalloy Question2 Whatistheprobabilityoffailureofthisalloyunderthesegivencircumstances COMPUTATIONOFAVERAGEANDSTANDARDDEVIATIONVALUES CD ROM 2020 3 26 Chapter7MechanicalProperties 38 PROPERTYVARIABILITYANDDESIGN SAFETYFACTORS 设计参数 安全系数 Designstress d Productofthecalcul