《[工学]吉林大学材料科学基础》由会员分享，可在线阅读，更多相关《[工学]吉林大学材料科学基础（41页珍藏版）》请在金锄头文库上搜索。
1、Chapter 7 Mechanical Properties,第七章 力学性质,吉林大学材料科学与工程学院 曹占义,2019/1/15,Chapter 7 Mechanical Properties,2,Mechanical properties: The mechanical behavior of a material reflects the relationship between its response or deformation to an applied load or force. Important mechanical properties: strength, ha
2、rdness, ductility, stiffness.,7.1 INTRODUCTION,力学性质,2019/1/15,Chapter 7 Mechanical Properties,3,Ways that load applied: Tension, Compression Shear torsion,7.2 CONCEPTS OF STRESS AND STRAIN,拉伸载荷,压缩载荷,剪切载荷,扭转载荷,2019/1/15,Chapter 7 Mechanical Properties,4,TENSION TESTS:,7.2 CONCEPTS OF STRESS AND STRAI
3、N,2019/1/15,Chapter 7 Mechanical Properties,5,COMPRESSION TESTS: SHEAR AND TORSIONAL TESTS:,7.2 CONCEPTS OF STRESS AND STRAIN,2019/1/15,Chapter 7 Mechanical Properties,6,GEOMETRIC CONSIDERATIONS OF THE STRESS STATE:,7.2 CONCEPTS OF STRESS AND STRAIN,2019/1/15,Chapter 7 Mechanical Properties,7,Stress
4、strain diagram and modulus of elasticity:,7.3 STRESSSTRAIN BEHAVIOR,2019/1/15,Chapter 7 Mechanical Properties,8,Force versus interatomic separation to explain the elastic deformation:,7.3 STRESSSTRAIN BEHAVIOR,2019/1/15,Chapter 7 Mechanical Properties,9,Elastic modulus depends on atomic bonding:,7.3
5、 STRESSSTRAIN BEHAVIOR,2019/1/15,Chapter 7 Mechanical Properties,10,Shear stress and strain,7.3 STRESSSTRAIN BEHAVIOR AND 7.4 ANELASTICITY,7.4 ANELASTICITY Anelastic deformation: Time-dependent elastic (non permanent) deformation.,滞弹性,2019/1/15,Chapter 7 Mechanical Properties,11,Poissons ratio,7.5 E
6、LASTIC PROPERTIES OF MATERIALS,2019/1/15,Chapter 7 Mechanical Properties,12,7.6 TENSILE PROPERTIES,YIELDING AND YIELD STRENGTH,2019/1/15,Chapter 7 Mechanical Properties,13,7.6 TENSILE PROPERTIES,TENSILE STRENGTH,2019/1/15,Chapter 7 Mechanical Properties,14,7.6 TENSILE PROPERTIES,DUCTILITY,塑性, 延展性,20
7、19/1/15,Chapter 7 Mechanical Properties,15,7.6 TENSILE PROPERTIES,Mechanical behavior for iron at three temperatures.,2019/1/15,Chapter 7 Mechanical Properties,16,7.6 TENSILE PROPERTIES,RESILIENCE,（回）弹性、弹性能,总应变能,2019/1/15,Chapter 7 Mechanical Properties,17,7.6 TENSILE PROPERTIES,6. TOUGHNESS,强韧性,For
8、 static situation: the area below the curve of - ,For dynamic (high strain rate) situation: notch toughness fracture toughness,For dynamic (high strain rate) situation: notch toughness 缺口冲击韧性 fracture toughness,For dynamic (high strain rate) situation: notch toughness 缺口冲击韧性 fracture toughness 断裂韧性,
9、2019/1/15,Chapter 7 Mechanical Properties,18,7.7 TRUE STRESS AND STRAIN,True Stress T,真实应力,True Strain 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,2019/1/15,Chapter 7 Mechanical Properties,19,7.7 TRUE STRESS AND STRAIN,True Stress T,真实应力,2019/1/15,Chapter 7 Mechanical Properties,20,7.7 TRUE STRESS AND STRAIN,True S
10、tress T,真实应力,2019/1/15,Chapter 7 Mechanical Properties,21,7.8 ELASTIC RECOVERY DURING PLASTIC DEFORMATION,Unloading cycles,2019/1/15,Chapter 7 Mechanical Properties,22,7.9 COMPRESSIVE, SHEAR, AND TORSIONAL DEFORMATION,COMPRESSIVE DEFORMATION, SHEAR DEFORMATION, TORSIONAL DEFORMATION,压缩变形,剪切变形,扭转变形,2
11、019/1/15,Chapter 7 Mechanical Properties,23,MECHANICAL BEHAVIORCERAMICS,7.10 FLEXURAL STRENGTH,(陶瓷材料的)抗弯强度,2019/1/15,Chapter 7 Mechanical Properties,24,MECHANICAL BEHAVIORCERAMICS,7.11 ELASTIC BEHAVIOR,(陶瓷材料的)弹性行为,2019/1/15,Chapter 7 Mechanical Properties,25,MECHANICAL BEHAVIORPOLYMERS,7.13 STRESSST
12、RAIN BEHAVIOR,(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,2019/1/15,Chapter 7 Mechanical Properties,26,MECHANICAL BEHAVIORPOLYMERS,7.13 STRESSSTRAIN BEHAVIOR,The mechanical characteristics of polymers, for the most part, are highly sensitive to the rate of deformation (strain rate), the tem
13、perature, and the chemical nature of the environment (the presence of water, oxygen, organic solvents, etc.).,2019/1/15,Chapter 7 Mechanical Properties,27,MECHANICAL BEHAVIORPOLYMERS,7.13 STRESSSTRAIN BEHAVIOR,(高分子材料的)应力_应变行为,屈服强度,抗张强度,2019/1/15,Chapter 7 Mechanical Properties,28,MECHANICAL BEHAVIOR
14、POLYMERS,7.13 STRESSSTRAIN BEHAVIOR,The mechanical characteristics of polymers, for the most part, are highly sensitive to the rate of deformation (strain rate), the temperature, and the chemical nature of the environment (the presence of water, oxygen, organic solvents, etc.).,材料:polymethyl methacr
15、ylate 聚甲基丙烯酸甲酯,In general, decreasing the rate of deformation has the same influence on the stressstrain characteristics as increasing the temperature; that is, the material becomes softer and more ductile.,2019/1/15,Chapter 7 Mechanical Properties,29,MECHANICAL BEHAVIORPOLYMERS,7.14 MACROSCOPIC DEF
16、ORMATION,(高分子材料的)宏观变形,7.15 VISCOELASTICITY 粘弹性(高分子材料的特性),2019/1/15,Chapter 7 Mechanical Properties,30,HARDNESS AND OTHER MECHANICAL PROPERTY CONSIDERATIONS,7.16 HARDNESS,Hardness. The measure of a materials resistance to deformation by surface indentation or by abrasion.,硬度,Mohs scale, which ranged from 1 on the soft end for talc to 10 (on the hard end) for diamond.,Measured hardnesses are only relative!,The reasons that Hardness tests are performed: 1. They are simple
