2 resultados para Academics and Scientific Careers
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
The efforts involved in developing a small satellite for scientific purposes in China in recent years are introduced in the present paper. The project is arranged on a case to case principle depending upon requirements and financial support. The space technology of a satellite and rockets, which have been developed over a relatively longer period in China, have been transferred to the scientific research of small satellites for improvement of the quality requirements. The surplus payloads of the rocket and satellite are used as the payloads of the small satellite and scientific experiments at a low cost. As an example, the project of balloon satellites for atmospheric research was successfully completed in 1991. The experience of the project management is of great benefit for further organization and arrangement of other projects. Opportunities exist for surplus payloads to be used in the future, and a small satellite for magnetospheric research will be launched in 1993.
Resumo:
Adiabatic shear localization is a mode of failure that occurs in dynamic loading. It is characterized by thermal softening occurring over a very narrow region of a material and is usually a precursor to ductile fracture and catastrophic failure. This reference source is the first detailed study of the mechanics and modes of adiabatic shear localization in solids, and provides a systematic description of a number of aspects of adiabatic shear banding. The inclusion of the appendices which provide a quick reference section and a comprehensive collection of thermomechanical data allows rapid access and understanding of the subject and its phenomena. The concepts and techniques described in this work can usefully be applied to solve a multitude of problems encountered by those investigating fracture and damage in materials, impact dynamics, metal working and other areas. This reference book has come about in response to the pressing demand of mechanical and metallurgical engineers for a high quality summary of the knowledge gained over the last twenty years. While fulfilling this requirement, the book is also of great interest to academics and researchers into materials performance.Table of Contents
| 1 | Introduction | 1 |
| 1.1 | What is an Adiabatic Shear Band? | 1 |
| 1.2 | The Importance of Adiabatic Shear Bands | 6 |
| 1.3 | Where Adiabatic Shear Bands Occur | 10 |
| 1.4 | Historical Aspects of Shear Bands | 11 |
| 1.5 | Adiabatic Shear Bands and Fracture Maps | 14 |
| 1.6 | Scope of the Book | 20 |
| 2 | Characteristic Aspects of Adiabatic Shear Bands | 24 |
| 2.1 | General Features | 24 |
| 2.2 | Deformed Bands | 27 |
| 2.3 | Transformed Bands | 28 |
| 2.4 | Variables Relevant to Adiabatic Shear Banding | 35 |
| 2.5 | Adiabatic Shear Bands in Non-Metals | 44 |
| 3 | Fracture and Damage Related to Adiabatic Shear Bands | 54 |
| 3.1 | Adiabatic Shear Band Induced Fracture | 54 |
| 3.2 | Microscopic Damage in Adiabatic Shear Bands | 57 |
| 3.3 | Metallurgical Implications | 69 |
| 3.4 | Effects of Stress State | 73 |
| 4 | Testing Methods | 76 |
| 4.1 | General Requirements and Remarks | 76 |
| 4.2 | Dynamic Torsion Tests | 80 |
| 4.3 | Dynamic Compression Tests | 91 |
| 4.4 | Contained Cylinder Tests | 95 |
| 4.5 | Transient Measurements | 98 |
| 5 | Constitutive Equations | 104 |
| 5.1 | Effect of Strain Rate on Stress-Strain Behaviour | 104 |
| 5.2 | Strain-Rate History Effects | 110 |
| 5.3 | Effect of Temperature on Stress-Strain Behaviour | 114 |
| 5.4 | Constitutive Equations for Non-Metals | 124 |
| 6 | Occurrence of Adiabatic Shear Bands | 125 |
| 6.1 | Empirical Criteria | 125 |
| 6.2 | One-Dimensional Equations and Linear Instability Analysis | 134 |
| 6.3 | Localization Analysis | 140 |
| 6.4 | Experimental Verification | 146 |
| 7 | Formation and Evolution of Shear Bands | 155 |
| 7.1 | Post-Instability Phenomena | 156 |
| 7.2 | Scaling and Approximations | 162 |
| 7.3 | Wave Trapping and Viscous Dissipation | 167 |
| 7.4 | The Intermediate Stage and the Formation of Adiabatic Shear Bands | 171 |
| 7.5 | Late Stage Behaviour and Post-Mortem Morphology | 179 |
| 7.6 | Adiabatic Shear Bands in Multi-Dimensional Stress States | 187 |
| 8 | Numerical Studies of Adiabatic Shear Bands | 194 |
| 8.1 | Objects, Problems and Techniques Involved in Numerical Simulations | 194 |
| 8.2 | One-Dimensional Simulation of Adiabatic Shear Banding | 199 |
| 8.3 | Simulation with Adaptive Finite Element Methods | 213 |
| 8.4 | Adiabatic Shear Bands in the Plane Strain Stress State | 218 |
| 9 | Selected Topics in Impact Dynamics | 229 |
| 9.1 | Planar Impact | 230 |
| 9.2 | Fragmentation | 237 |
| 9.3 | Penetration | 244 |
| 9.4 | Erosion | 255 |
| 9.5 | Ignition of Explosives | 261 |
| 9.6 | Explosive Welding | 268 |
| 10 | Selected Topics in Metalworking | 273 |
| 10.1 | Classification of Processes | 273 |
| 10.2 | Upsetting | 276 |
| 10.3 | Metalcutting | 286 |
| 10.4 | Blanking | 293 |
| Appendices | 297 | |
| A | Quick Reference | 298 |
| B | Specific Heat and Thermal Conductivity | 301 |
| C | Thermal Softening and Related Temperature Dependence | 312 |
| D | Materials Showing Adiabatic Shear Bands | 335 |
| E | Specification of Selected Materials Showing Adiabatic Shear Bands | 341 |
| F | Conversion Factors | 357 |
| References | 358 | |
| Author Index | 369 | |
| Subject Index | 375 |
