权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Molecular Dynamics Investigation of Physical Phenomena in Microtribology and Ultraprecision Machining

微摩擦学和超精密加工中物理现象的分子动力学研究

基本信息

批准号：
05650137
负责人：
MAEKAWA Katsuhiro
金额：
$ 1.54万
依托单位：
Ibaraki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The role of friction in nano-scale machining has been investigated using a new molecular dynamics simulation model based on the Nose-Hoover method, in which the restricted analytical region moves together with the tool advancement. Orthogonal machining of a (111) plane of a copper single crystal by a diamond-like tool with 3 nm edge radius has been simulated, where the uncut chip thickness and the cutting speed was set at 1 nm and 20 m/s, respectively, and the cutting direction was taken to be [101]. Morse type potentials with various magnitudes of the cohesion energy were postulated to approximate the friction at the tool-workpiece interface as well as the materials themselves.The major results obtained are as follows :(1) Chip formation in the nano-scale metal machining is similar to that observed in macro-scale machining. With increase of the bond energy at the interface, both chip thickness and contact length between the chip and tool become larger, leading to increases in the average cutting forces and the temperature in the system. Besides, the machined surface is subjected to severe damages.(2) Tool wear has also been modelled by taking into account the tool consisting of the carbon atoms which have a reduced cohesion energy and obey Newton's equation of motion. The atomistic wear proceeds with the repetition of inter-diffusion between the workpiece and tool atoms and re-adhesion of the worn atoms to the tool.(3) The shape of interface potential and the tool wear distributions also affect the minimum thickness of cut and the depth of the region where the displaced workpiece atoms exist : two and ten atomic layrs are their minimums, respectively.(4) Existing atomistic defects such as vacancies and dislocations increase the cutting force and enlarge the atomistic disturbance in the workpiece as well, which is due to the interaction between the defects and the dislocations emerging from the cutting edge.

利用基于Nose-Hoover方法的分子动力学模拟模型研究了摩擦在纳米加工中的作用，该模型中的受限分析区域随着刀具的推进而移动。采用刃口半径为3 nm的类金刚石刀具，在切屑厚度为1 nm、切割速度为20m/S、切割方向为[101]的条件下，模拟了铜单晶(111)面的正交切削加工。假设具有不同结合能的Morse型势能近似刀具-工件界面的摩擦力和材料本身的摩擦力。主要结果如下：(1)纳米金属加工中切屑的形成与宏观加工中观察到的切屑形成相似。随着界面结合能的增加，切屑厚度和切屑与刀具之间的接触长度都变大，导致平均切削力和系统温度增加。此外，已加工表面还受到严重的损伤。(2)刀具磨损的建模也考虑了由碳原子组成的刀具，这些碳原子具有降低的结合能并服从牛顿运动方程。(3)界面电势形状和刀具磨损分布也影响最小切削层厚度和所在区域的深度：两层和十层原子层分别是它们的最小值。(4)空位和位错等原子性缺陷的存在增加了切削力，增大了原子性扰动，这是由于缺陷和从刀具刃口产生的位错之间的相互作用。