An all-in-one guide to the theory and applications of plasticity in metal forming, featuring examples from the automobile and aerospace industries

* Provides a solid grounding in plasticity fundamentals and material properties

* Features models, theorems and analysis of processes and relationships related to plasticity, supported by extensive experimental data

* Offers a detailed discussion of recent advances and applications in metal forming

Z. R. Wang, Harbin Institute of Technology, China.
W. L. HU, Troy Design and Manufacturing Co., USA.
S. J. Yuan, Harbin Institute of Technology, China.
X. S. WANG, Harbin Institute of Technology, China.

Inhalt

Preface xiii

1 Fundamentals of Classical Plasticity 1

1.1 Stress 1

1.1.1 The Concept of Stress Components 1

1.1.2 Description of the Stress State 2

1.1.2.1 Stresses on an Arbitrary Inclined Plane 2

1.1.2.2 Stress Components on an Oblique Plane 4

1.1.2.3 Special Stresses 6

1.1.2.4 Common Stress States 7

1.1.3 Stress Tensors and Deviatoric Stress Tensors 7

1.1.4 Mohr Stress Circles 9

1.1.4.1 Mohr Circles for a Two-Dimensional Stress System 9

1.1.4.2 Mohr Circles for a Three-Dimensional Stress System 12

1.1.5 Equations of Force Equilibrium 13

1.2 Strain 15

1.2.1 Nominal Strain and True Strain 15

1.2.2 Strain Components as Functions of Infinitesimal Displacements 17

1.2.3 The Maximum Shear Strains and the Octahedral Strains 20

1.2.4 Strain Rates and Strain Rate Tensors 21

1.2.5 Incompressibility and Chief Deformation Types 23

1.3 Yield Criteria 25

1.3.1 The Concept of Yield Criterion 25

1.3.2 Tresca Yield Criterion 26

1.3.3 Mises Yield Criterion 26

1.3.4 Twin Shear Stress Yield Criterion 27

1.3.5 Yield Locus and Physical Concepts of Tresca, Mises, and Twin Shear Stress Yield Criteria 27

1.3.5.1 Interpretation of Tresca Yield Criterion 29

1.3.5.2 Interpretation of Twin Shear Stress Yield Criterion 30

1.3.5.3 Interpretation of Mises Yield Criterion 31

1.4 A General Yield Criterion 33

1.4.1 Representation of General Yield Criterion 33

1.4.2 Yield Surface and Physical Interpretation 34

1.4.3 Simplified Yield Criterion 34

1.5 ClassicalTheory about Plastic StressStrain Relation 35

1.5.1 Early Perception of Plastic Stress Strain Relations 36

1.5.2 Concept of the Gradient-Based Plasticity and Its Relation with Mises Yield Criterion 37

1.5.2.1 Concept of the Plastic Potential 37

1.5.2.2 Physical Interpretation of the Plastic Potential 38

1.5.2.3 Physical Interpretation of Mises Yield Function (Plastic Potential) 39

1.6 Effective Stress, Effective Strain, and Stress Type 42

1.6.1 Effective Stress 42

1.6.2 Effective Strain 42

1.6.3 Stress Type 44

References 44

2 Experimental Research on Material Mechanical Properties under Uniaxial Tension 47

2.1 StressStrain Relationship of Strain-Strengthened Materials under Uniaxial Tensile Stress State 47

2.2 The StressStrain Relationship of the Strain-Rate-Hardened Materials in Uniaxial Tensile Tests 48

2.3 StressStrain Relationship in Uniaxial Tension during Coexistence of Strain Strengthening and Strain Rate Hardening 50

2.4 Bauschinger Effect 56

2.5 Tensile Tests for Automotive Deep-Drawing Steels and High-Strength Steels 57

2.5.1 Test Material and Experiment Scheme 57

2.5.2 True StressStrain Curves in Uniaxial Tension 58

2.5.3 Mechanical Property Parameters of Sheets 58

2.5.3.1 Strain-Hardening Exponentn 59

2.5.3.2 Lankford ParameterR 62

2.5.3.3 Plane Anisotropic Exponent R 62

2.5.3.4 Yield-to-Tensile Ratio s¨Mb 62

2.5.3.5 Uniform Elongation m 62

2.6 Tensile Tests on Mg-Alloys 63

2.7 Tension Tests on Ti-Alloys 63

2.7.1 Mechanical Properties of Ti-3Al-2.5V Ti-Alloy Tubes at High Temperatures 65

2.7.2 Strain Hardening of Ti-3Al-2.5V Ti-Alloy in Deformation at High Temperatures 69

References 71

3 Experimental Research on Mechanical Properties of Materials under a Non-Uniaxial Loading Condition 73

3.1 P-p Experimental Results ofThin-Walled Tubes 73

3.1.1 Lode Experiment 73

3.1.2 P-p Experiments onThin-Walled Tubes Made of Superplastic Materials 78

3.1.2.1 Experiment Materials and Specimens 78

3.1.2.2 Loading Methods 80

3.1.2.3 Experimental Results and Analysis 80

3.1.3 Experiments on Tubes Subjected to Internal Pressure and Axial Compressive Forces 86

3.1.3.1 Experimental Device 86