Materials and Structures under Shock and Impact

Materials and Structures under Shock and Impact In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site. This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending to the whole of the structure. The first part of the book is devoted to the study of solid dynamics where nonlinear behaviors come into play. The second part covers structural dynamics and the evaluation of the transient response introduced at the global scale of a construction. Practical methods, simplified methods and methods that are in current use by engineers are also proposed throughout the book.

Table of Contents:
Introduction xi PART 1. DYNAMICS OF SOLIDS 1 Chapter 1. Motion within Solids 3 1.1. Representation of the medium 3 1.2. Elastodynamic equations 8 1.3. One-dimensional waves 12 1.4. Harmonic waves 16 1.5. Viscoelasticity 23 Chapter 2. Shocks in Solids 37 2.1. Discontinuity of stress and velocity 37 2.2. Wave course 42 2.3. Shocks of solids 50 2.4. Shocks on viscoelastic solids 59 Chapter 3. Waves and Shocks in a Nonlinear Medium 67 3.1. Irreversible phenomena 67 3.2. Adiabatic shear 76 3.3. Propagation in uniaxial stress state 80 3.4. Uniaxial strain state 88 3.5. Shock waves 95 Chapter 4. Dynamic Materials Testing 103 4.1. Dynamic testing 103 4.2. Hopkinson pressure bars 106 4.3. Testing by direct impact 112 4.4. Taylor impact test 113 4.5. Plate impact 115 PART 2. DYNAMIC OF STRUCTURES 117 Chapter 5. Impact on a Simple Structure 119 5.1. Basic structure119 5.2. Shock response spectrum 124 5.3. Iso-damage curves 135 5.4. Modeling a real structure 138 Chapter 6. Collisions of Structures 153 6.1. Shocks on elastic structures 153 6.2. Shock with crushing 159 6.3. Classification of shocks 168 Chapter 7. Explosions and Blasts 173 7.1. Accidental explosions 173 7.2. Pressure waves 179 7.3. Action of an explosion on a structure 188 7.4. Blast-structure coupling 194 Chapter 8. Mechanical Response of Beams 203 8.1. Dynamic beam models 203 8.2. Impacts on beams 211 8.3. Calculation by modal superposition 226 8.4. Dynamic buckling 239 Chapter 9. Responses of Multiple Degree of Freedom Structures 245 9.1. Modeling through a discrete system 245 9.2. Resolution by modal superposition 249 9.3. Fluid–structure coupling 255 Chapter 10. Response of a Nonlinear Structure 267 10.1. Nonlinear behavior of structures 267 10.2. Nonlinear system with one degree of freedom 281 10.3. The case of elastoplastic behavior 284 10.4. Approach of response to a violent impact 292 Bibliography 299 Index 309

About the Author :
Patrice Bailly is Professor at the Ecole nationale supérieure d’ingénieurs de Bourges in France, where he is responsible for the topic of material and structural dynamics at the PRISME laboratory.