磨粒刻划单晶SiC的SPH与FEM耦合仿真分析

Analysis of SPH and FEM Coupling Simulation of Abrasive Grain Scratching Single Crystal SiC

目的进一步理解金刚石线锯加工硬脆晶体材料的去除特性。方法采用SPH与FEM耦合算法,分析磨粒刻划单晶碳化硅工件过程中的材料去除动态响应,研究不同磨粒压入深度与几何形状条件对磨粒接触力、工件刻划表面形貌与应力分布的影响规律,分析磨粒恒定深度刻划与变深度刻划两种方式下磨粒刻划工件材料的动态响应。结果磨粒接触力的各方向分量均随刻划时间发生波动,其中x与z轴方向的磨粒接触力随时间的变化趋势相近,平稳刻划时段的磨粒接触力均值拟合方程分别为f_(x)=3.0956h^(2.7264),f_(z)=11.3813h^(2.6214)。磨粒压入深度是影响刻划过程中工件刻划截面形貌及应力分布的主要因素。相较于圆锥体磨粒,球体磨粒刻划后的工件材料截面形貌更粗糙,但工件材料的变形及损伤层深度更小。在磨粒变深度刻划方式下,随着磨粒压入深度的增加,刻划过程中的工件材料发生了脆塑转变。结论在保证材料去除率的条件下,需降低磨粒压入深度,以降低磨粒接触力,获得更平整的工件表面刻划形貌与更低的等效应力。

This paper aims to further understand the removal characteristics of hard and brittle crystal materials processed by diamond wire saws.The SPH and FEM coupling algorithm is used to analyze the dynamic response of material removal during the process of abrasive grain scratching a single crystal silicon carbide workpiece.The influence of abrasive particle contact force,workpiece surface morphology,and stress distribution under different abrasive grain depths and geometric shapes are studied.Two kinds of scratching methods: the constant depth scratching and the variable depth scratching of abrasive grains are analyzed on the dynamic response behavior of workpiece materials.The calculation results show that the components of the abrasive grain contact forces in all directions fluctuate with the scratching process.The x-axis direction and the z-axis direction of the abrasive particle contact forces have similar changes with time,and the fitted equations of the average abrasive particle contact forces during the smooth scratching period are respectively f_(x)=3.0956 h^(2.7264) and f_(z)=11.3813 h^(2.6214).The grain depth of abrasive particles is the main factor affecting the morphology and stress distribution of the workpiece during the scratching process.Compared with the conical abrasive grain,the cross-sectional morphology of the workpiece material scratched by spherical abrasive grain is rougher,but the deformation and damage layer depth of the workpiece material is smaller.The material response of the workpiece under variable depth scratching reflects the brittle-plastic transition of the workpiece as the depth of abrasive grain increases.The research results show that under the condition of ensuring the material removal rate,it is necessary to reduce the scratching depth of the abrasive grains to lower the contact force of the abrasive grains and to obtain a smoother surface morphology and lower equivalent stress.