Simulation of Nano-scale Material Tensile Test and Research on the Cutting Force of Nano-scale Orthogonal Cutting Model

• Main Authors: Chen Zhen-Da, 陳振達
• Other Authors: Lin Zone-Ching
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/67608751681014429884

碩士 === 國立臺灣科技大學 === 自動化及控制研究所 === 91 === Abstract This thesis first uses molecular dynamics to simulate nano thin film tensile test, and then obtains the stress-strain curve in the simulative experiment. After regression process, this stress-strain curve can be transformed to flow stress-strain equation. Besides, molecular dynamics theory is adopted to simulate the status of 2D orthogonal cutting, to as to ask for atom displacement. With the usage of shape function concept in the finite element method, the equivalent strain of nodal atoms and elements in the atomic scale is calculated. The flow stress-strain equation acquired after implementing the simulative experiment of nano-scale tensile test, as well as regression process can be used to calculate the equivalent stress occurred under the equivalent strain. This study establishes the calculative model of the cutting force of nano-scale orthogonal cutting, and uses two kinds of materials, that is, copper and nickel, to proceed with simulation. The cutting force occurred during the nano-scale cutting, and the changes of cutting force under different status can then be calculated. Next, compare the value of cutting force acquired by simulation with Ikawa [25], so as to identity that the value of cutting force proposed herein is reasonable. When conducting the nano-scale material tensile test, simulate the status of different materials under the single-axis proportional tension, and draw the stress-strain curve. Regard the acquired stress as the equivalent stress , and the strain as the equivalent strain . Subsequently, the regressed equivalent strain-stress equation by means of equivalent stress-strain curve is considered as flow stress-strain equation. Further compare this value with Miyazaki’s [45] maximum stress value of the equivalent stress in times of material tension simulation, so as to identity that the equivalent stress proposed herein is reasonable. Also proceed with sensitivity analysis towards the trunction radius , so as to investigate into the effect of the value of trunction radius . Then compare this value with the regressed stress-strain equation. It is discovered that the larger the value of trunction radius , the smaller would be the induced value of stress. Also, the curve slope of the stress-strain curve is relatively smaller. Finally, calculate the stress and strain value of the nano-cutting of different materials. First of all, simulate the nano-scale cutting to ask for the value of equivalent strain. Then lead in the flow stress-strain equation by the regression of different trunction radius , so as to observe the changes of the equivalent stress-strain values of copper and nickel. The result of this study helps to understand the nanometer cutting behavior, indicating a new direction to nano-scale processing technology.