Dynamic Damage and Fragmentation

Engineering structures may be subjected to extreme high-rate loading conditions, like those associated with natural disasters (earthquakes, tsunamis, rock falls, etc.) or those of anthropic origin (impacts, fluid-structure interactions, shock wave transmissions, etc.). Characterization and modeling of the mechanical behavior of materials under these environments is important in predicting the response of structures and improving designs. This book gathers contributions by eminent researchers in academia and government research laboratories on the latest advances in the understanding of the dynamic process of damage, cracking and fragmentation. It allows the reader to develop an understanding of the key features of the dynamic mechanical behavior of brittle (e.g. granular and cementitious), heterogeneous (e.g. energetic) and ductile (e.g. metallic) materials.

Auteur

David Edward Lambert is a member of the scientific and professional cadre of Senior Executives, and Chief Scientist of the Air Force Research Laboratory, Munitions Directorate, Eglin, USA.

Crystal L. Pasiliao is a Senior Research Scientist at the Air Force Research Laboratory, Munitions Directorate, Eglin, USA.

Benjamin Erzar is a Senior Research Scientist at the Commissariat à l'Energie Atomique, Gramat, France.

Benoit Revil-Baudard is a Research Scientist in the Department of Mechanical and Aerospace Engineering at the University of Florida, REEF, Shalimar, USA.

Oana Cazacu is Professor in the Department of Mechanical and Aerospace Engineering at the University of Florida, REEF, Shalimar, USA.

Contenu

Preface xiii

Chapter 1. Some Issues Related to the Modeling of Dynamic Shear Localization-assisted Failure 1
*Patrice LONGÈRE*

1.1. Introduction 1

1.2. Preliminary/fundamental considerations 3

1.2.1. Localization and discontinuity 3

1.2.2. Isothermal versus adiabatic conditions 6

1.2.3. Sources of softening 9

1.2.4. ASB onset 22

1.2.5. Scale postulate 26

1.3. Small-scale postulate-based approaches 27

1.3.1. Material of the band viewed as an extension of the solid material behavior before ASB onset 28

1.3.2. Material of the band viewed as a fluid material 29

1.3.3. ASB viewed as a damage mechanism 31

1.3.4. Assessment 32

1.4. Embedded band-based approaches (large-scale postulate) 33

1.4.1. Variational approaches 34

1.4.2. Enriched finite element kinematics 38

1.4.3. Enriched constitutive model 41

1.4.4. Discussion 43

1.5. Conclusion 44

1.6. Acknowledgments 45

1.7. References 45

Chapter 2. Analysis of the Localization Process Prior to the Fragmentation of a Ring in Dynamic Expansion 53
*Skander EL MAÏ, Sébastien MERCIER and Alain MOLINARI*

2.1. Introduction 53

2.1.1. Fragmentation experiments 54

2.1.2. Fragmentation theories 54

2.2. An extension of a linear stability analysis developed in [MER 03] 59

2.2.1. Position of the problem 59

2.2.2. Classical linear stability analysis 60

2.2.3. Evolution of the cross-section perturbation 62

2.2.4. Analysis of the potential sites of necking 65

2.3. Outcomes of the approach 70

2.3.1. Effects of the loading velocity on neck spacing distribution 70

2.3.2. Effects of an imposed dominant mode in the initial perturbation 72

2.3.3. Comparison of the approach with numerical simulations 83

2.4. Conclusion 89

2.5. References 90

Chapter 3. Gradient Damage Models Coupled with Plasticity and Their Application to Dynamic Fragmentation 95
*Arthur GEROMEL FISCHER and Jean-Jacques MARIGO*

3.1. Introduction 95

3.2. Theoretical aspects 96

3.2.1. Gradient damage models 96

3.2.2. Damage coupled with plasticity 106

3.2.3. Dynamic gradient damage 117

3.3. Numerical implementation 122

3.4. Applications 123

3.4.1. 1D fracture 124

3.4.2. Material behavior 124

3.4.3. Dimensionless parameters 126

3.4.4. 1D period bar 131

3.4.5. Cylinder under internal pressure 135

3.5. Conclusion 138

3.6. References 139

Chapter 4. Plastic Deformation of Pure Polycrystalline Molybdenum 143
*Geremy J. KLEISER, Benoit REVIL-BAUDARD and Oana CAZACU*

4.1. Introduction 143

4.2. Quasi-static and dynamic data on a pure polycrystalline Mo 144

4.2.1. Analysis of the quasi-static uniaxial tension test results on smooth specimens 147

4.2.2. Split Hopkinson pressure bar data 154

4.2.3. Taylor cylinder impact data 155

4.3. Constitutive model for polycrystalline Mo 158

4.4. Predictions of the mechanical response 162

4.4.1. FE. predictions of the quasi-static uniaxial tensile response for notched specimens 162

4.5. Conclusions 172

4.6. References 173

Chapter 5. Some Advantages of Advanced Inverse Methods to Identify Viscoplastic and Damage Material Model Parameters 177
*Bertrand LANGRAND, Delphine NOTTA-CUVIER, Thomas FOUREST and Eric MARKIEWICZ*

5.1. Introduction 177

5.2. Experimental devices for material characterization over a large range of strain rates 180

5.3. Identification of elasto-viscoplastic and damage material Parameters 184

5.3.1. Direct approach for material parameter identification 184

5.3.2. Inverse approaches for material parameter identification 192

5.4. Conclusions 204 &l...