Rheology, Physical and Mechanical Behavior of Materials 1

Preface xi

Chapter 1 Dynamic Plasticity: Dislocations 1

1.1 Introduction: how to describe plasticity? 1

1.2 Strain speed: epsilon (gamma for shearing) 7

1.3 The microstructural mechanisms of plasticity 16

Chapter 2 Obstacles and Mechanisms of Crossings 59

2.1 Obstacles 60

2.2 Nature and resistance of obstacles 61

2.3 Example of measuring dislocation speeds 62

2.4 Microstructural mechanisms of the deformation rate 67

2.5 Mechanisms due to obstacles: hardening mechanisms 68

2.6 Athermal mechanism of the movement of a dislocation 116

2.7 Thermally activated mechanism of the movement of a dislocation 122

2.8 The viscous friction mechanism 129

Chapter 3 Dynamic Flows for Monocrystals and Polycrystals 137

3.1 Type of monocristal and polycrystal dynamic shear test samples (anisotropy and isotropy at high speeds) 138

3.2 The tensor of the shock stresses 139

3.3 Study of strain on a polycrystal 140

3.4 Dynamic flows by electromagnetic shocks, polycrystalline aluminum A5 140

3.5 The case of six polycrystals 142

3.6 The case of monocrystals 143

3.7 Models for CFCs 147

3.8 Dynamics of flows shown using an ultra-fast camera 152

3.9 Viscoplasticity 161

3.10 References for viscoplasticity 170

Chapter 4 Limits to Static and Dynamic Formability 173

4.1 Plastic instability 173

4.2 Forming by pressing 181

4.3 Damage: area between necking and fracture, the case between Forming Limit Curves (FLCs) and Fracture Forming Limit Curves (FFLCs) 190

4.4 Limit of the formability during necking (FLCs) and during fracture (FFLCs): influence of the strain rate 196

Chapter 5 Dynamic Resistance to Mechanical Shocks 219

5.1 Shock stresses 219

5.2 Resilience test 227

5.3 Typical loads, stress waves 251

5.4 Dynamic tests, Hopkinson technique, laws of behavior 264

Appendix A Primary Times of Mechanisms 289

References 313

Index 319