4 resultados para 341.73
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Resumo:
<正> 眩晕是临床比较常见的一个病症。对于眩晕的病情轻重和治疗效果的评定,主要依靠病人的主诉与医生的判断,目前还没有客观指标。为此,我们住中医辨证治疗眩晕的研究中,用平衡仪对73例眩晕患者进行了平衡试验观察,现将观察结果报告于下。方法和结果一、观察方法眩晕的检测工具为平衡仪(又称重心仪)Gravicorder,由检测平台和放大器二部分组成。检测平台是一块铸铝板(800×800×200毫米~3),它的四角放在四个负荷传感器(BLR-1
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 |
Resumo:
Semiconducting manganese silicide, Mn27Si47 and Mn15Si26, were obtained using mass-analyzed low energy dual ion beam epitaxy technique, Auger electron spectroscopy depth profiles showed that some of the Mn ions were deposited on single-crystal silicon substrate and formed a 37.5 nm thick Mn film, and the other Mn ions were successfully implanted into the Si substrate with the implantation depth of 618 nm. Some samples were annealed in the atmosphere of flowing N-2 at 840 degreesC. X-ray diffraction measurements showed that the annealing was beneficial to the formation of Mn27Si47 and Mn15Si26 (C) 2001 Published by Elsevier Science B.V.
