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| 1 | How to identify dislocations in molecular dynamics simulations?显示文摘Dislocations are of great importance in revealing the underlying mechanisms of deformed solid crystals.With the development of computational facilities and technologies,the observations of dislocations at atomic level through numerical simulations are permitted.Molecular dynamics(MD)simulation suggests itself as a powerful tool for understanding and visualizing the creation of dislocations as well as the evolution of crystal defects.However,the numerical results from the large-scale MD simulations are not very illuminating by themselves and there exist various techniques for analyzing dislocations and the deformed crystal structures.Thus,it is a big challenge for the beginners in this community to choose a proper method to start their investigations.In this review,we summarized and discussed up to twelve existing structure characterization methods in MD simulations of deformed crystal solids.A comprehensive comparison was made between the advantages and disadvantages of these typical techniques.We also examined some of the recent advances in the dynamics of dislocations related to the hydraulic fracturing.It was found that the dislocation emission has a significant effect on the propagation and bifurcation of the crack tip in the hydraulic fracturing. | LI Duo WANG Feng Chao YANG Zhen Yu ZHAO Ya Pu | 2014 | Science China(Physics,Mechanics & Astronomy)2014，57，12： | 11 |
| 2 | Molecular dynamics simulation of single crystal Nickel nanometric machining显示文摘Molecular dynamics simulation is carried out to study the nanometric machining of single crystal Nickel(Ni). Through an investigation of atomic displacement and the variation of cutting force, it is found that the latter is in accordance with the number variation of elastic displaced atoms in the workpiece. It is further found that the generation of complex stacking faults is the predominant cause of cutting force fluctuation, and the stacking faults with complex structures lead to work-hardening. The temperature of the cutting tool and workpiece is studied during the machining process. It is concluded that the selection of averaging steps has a significant influence on the system temperature distribution. Thus, the time-spatial averaging method, which has a high accuracy and consistency in temperature distribution, is proposed. | ZHU Zong Xiao GONG YaDong ZHOU Yun Guang GAO Qi | 2016 | Science China(Technological Sciences)2016，59，6： | 6 |
| 3 | Chip formation dependence of machining velocities in nano-scale by molecular dynamics simulations显示文摘In this study, molecular dynamics simulations were carried out to study the effect of machining velocities on the mechanism of chip formation in nano-metric copper. A wide range of cutting velocities was performed from 10 to 2000 m/s, and the microstructure's evolution from a crystalline state to an amorphous state was studied. At the low machining velocity, dislocations were generated from the surface in front of the tool, and the immobile dislocation deduced by the cross slip of dislocation was observed. At the high machining velocity, no crystal dislocation nucleated, but instead disorder atoms were found near the tool. Temperature near the tool region increased with the increasing machining velocities, and the temperature had an important effect on the phase transition of the crystal structure. | SU Hao TANG Qi Heng | 2014 | Science China(Technological Sciences)2014，57，12： | 5 |
| 4 | Atomic simulations of influence of twinning on crack propagation of Al显示文摘Molecular dynamics simulation was performed to investigate the influence of twin boundary(TB) spacing on crack propagation of Al.This study reveals the orientation of initial crack may affect the mechanism of crack growth obviously.TB strengthens Al when the crack orientation is parallel with TB because of the hinderance of TB to the emission of the dislocations.The results indicate that there is an optimal TB spacing for mechanical properties of the Al,exhibiting reverse HP(Hall-Petch) and HP effect when the TB spacing is near the critical TB spacing.Furthermore,we find that there is a yield strength hardening effect in nanotwinned Al when the crack orientation is perpendicular to the TB,and the Young's modulus is smaller in the nanotwinned Al than that of twin free Al.The studies also demonstrate that this distinctive deformation behavior is related to nucleation of dislocations and the repulsive force of TB to the dislocations and crack propagation,as well as the distance between the crack tip and the TB. | AN MinRong SONG HaiYang | 2013 | Science China(Physics,Mechanics & Astronomy)2013，56，10： | 4 |
| 5 | Study of nanoscratching of polymers by using molecular dynamics simulations显示文摘Molecular dynamic simulations are performed to study the nanoscratching behavior of polymers.The effects of scratching depth,scratching velocity and indenter/polymer interaction strength are investigated.It is found that polymer material in the scratching zone around the indenter can be removed in a ductile manner as the local temperature in the scratching zone exceeds glass transition temperature Tg.The recovery of polymer can be more significant when the temperature approaches or exceeds Tg.The tangential force,normal force and friction coefficient increase as the scratching depth increases.A larger scratching velocity leads to more material deformation and higher pile-up.The tangential force and normal force are larger for a larger scratching velocity whereas the friction coefficient is almost independent of the scratching velocities studied.It is also found that stronger indenter/polymer interaction strength results in a larger tangential force and friction coefficient. | YUAN DanDan ZHU PengZhe FANG FengZhou QIU Chen | 2013 | Science China(Physics,Mechanics & Astronomy)2013，56，9： | 4 |
| 6 | Research on the nanometric machining of a single crystal nickel via molecular dynamics simulation显示文摘Molecular dynamics simulations are employed to study the nanometric machining process of single crystal nickel. Atoms from different machining zones had different atomic crystal structures owing to the differences in the actions of the cutting tool. The stacking fault tetrahedral was formed by a series of dislocation reactions, and it maintained the stable structure after the dislocation reactions. In addition, evidence of crystal transition and recovery was found by analyzing the number variations in different types of atoms in the primary shear zone, amorphous region, and crystalline region. The effects of machining speed on the cutting force, chip and subsurface defects, and temperature of the contact zone between the tool and workpiece were investigated. The results suggest that higher the machining speed, larger is the cutting force. The degree of amorphousness of chip atoms and the depth and extent of subsurface defects increase with the machining speed. The average friction coefficient first decreases and then increases with the machining speed because of the temperature difference between the chip and machining surface. | GONG Ya Dong ZHU Zong Xiao ZHOU Yun Guang SUN Yao | 2016 | Science China(Technological Sciences)2016，59，12： | 4 |
| 7 | Preface to the Special Issue on Physical Mechanics显示文摘The 23rd International Congress of Theoretical and Applied Mechanics (ICTAM2012) will be held in Beijing, China, from August 19 to 24, 2012. The Congress (ICTAM), as the most authoritative and comprehensive conference in mechanics in | ZHAO YaPu Professor Guest Editor Institute of Mechanics,Chinese Academy of Sciences | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，6： | 3 |
| 8 | Connecting microscopic structure and macroscopic mechanical properties of structural materials from first-principles显示文摘Computer simulation plays a critical role in connecting microscopic structure and macroscopic mechanical properties of structural material,which is a key factor that needs to be considered in design of such kind of material.Via the quantum mechanics first-principles calculations,one can gain structure,elastic constant,energetics,and stress of selected material system,based on which one is able to predict the mechanical properties or provide useful insights for the mechanical properties of the materials.This can be done either directly or in combination with the empirical criterions.This paper reviews the recent research advances on the attempts to predict the mechanical properties of structural materials from first principles. | LU GuangHong ZHANG Lei | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，12： | 2 |
| 9 | 微观天然橡胶摩擦性能研究显示文摘采用分子动力学方法模拟了刚性探头在天然橡胶基底表面滑动摩擦过程,利用模型体积随温度变化关系求得玻璃化转变温度(Tg)。重点讨论了探头与基底作用方式、温度以及滑动速度对摩擦过程的影响。结果表明,相比于强排斥作用,强黏着作用下基底对探头存在黏着力,在探头受到相等载荷时会获得更大的压入深度,加剧磨损,同时阻碍了探头切向运动,需要增大切向力平衡;温度低于Tg时,温度越低磨损程度越大,摩擦力变化趋势正相反;温度高于Tg时,摩擦力随温度升高而下降,磨损加剧;滑动速度增加,基底形变阻力增大,接触区域摩擦热无法及时释放,材料硬度降低,摩擦力小幅上升,表面磨损加剧。 | 柳春洋 何燕 | 2016 | 弹性体2016，26，4： | 1 |
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