纳米尺度下切削过程的准连续介质力学模拟

采用准连续介质力学方法模拟了镍单晶体刀具在单晶铜工件上的切削过程,深入分析了切削过程中的能量演化?应力场变化和原子位移情况等因素.结合切削过程中位错滑移等塑性行为和原子径向分布理论,揭示了切屑产生的机理,证实了切削过程中已加工表面和体相晶体结构的非晶态变化是切屑产生的主要原因.通过对纳米切削过程不同阶段的模拟表明:刀具的耕犁作用下剪切带的形成和扩展是切屑形成的初始阶段;变质层的产生是纳米切削的中间阶段并构成了加工表面组织;储存在变形晶格中的变形能超过一定值时,晶格被打破,形成非晶态结构是切屑形成的最终阶段.

Quasicontinuum Simulations of Nano-cutting Process

The nano-cutting process of a single crystal nickel tip into single crystal copper was studied by using quasicontinuum (QC) method. The changes of energy evolution, the stress field and atomic displacement during the cutting process were investigated. The mechanism of the chip formation was numerically revealed by combining the plastic behavior of dislocation slip with the theory of atom radial distribution. The simulated results showed that the chip formation phenomenon was resulted from the amorphization of the processed surfaces and bulk. The simulated results of different stages during nano-cutting process indicated that the nucleation and propagation of the chip shear zone occurred at the initial stage. The second stage was the formation of the metamorphic layer, which constructed the microstructure of the processed surfaces. When the transform energy stored in the crystal lattices exceeded a critical value, the crystal attics were broken. At that time, the amorphous structures were formed and considered as the last stage