毫秒激光辐照单晶硅的晶体塑性有限元模拟
时间:2018-11-23 21:54 来源:毕业论文 作者:毕业论文 点击:次
| 摘要本文基于热传导方程、晶体塑性应变理论建立了三文的计算模型。在充分考虑单晶硅材料各向异性和各物理参数随温度变化的基础上，运用COMSOL有限元分析软件模拟了长脉冲激光辐照单晶硅的瞬态温度场和热应力场分布。通过对单晶硅损伤实验与数值模拟结果的对比，进一步解释单晶硅表面解理裂纹的产生机制。结果发现：在整个作用区域内，光斑辐照的中心点温度最高，沿轴向和径向温度不断衰减，温度的分布主要趋于材料表层光斑大小的区域内并呈锥形分布。光斑中心与其它区域的温度梯度随辐照时间不断增加，继而造成热应力的产生。当12个不同滑移系的剪切应力超过单晶硅的屈服强度时，材料发生滑移，且塑性滑移最初发生在光斑中心沿z轴偏下的位置，考虑所有类型滑移系的共同作用，整个滑移区域呈现碗状分布。不同滑移之间的相互重叠表现为沿[110]和 方向相互垂直的解理裂纹。30547 关键词 毫秒激光 单晶硅 损伤 晶体塑性 有限元 毕业论文设计说明书外文摘要 Title Simulation of single-crystal silicon irradiated by a millisecond laser using crystal plasticity FEM Abstract A three-dimensional calculation model is established based on the theory of heat conduction equation and crystal plasticity strain.On the basis of fully considering the anisotropy of single-crystal silicon material and the physical parameters changing with temperature.Using COMSOL finite element analysis software to simulate the distribution of transient temperature field and thermal stress field of single-crystal silicon irradiated by a long pulse laser.Comparing experiment with the results of numerical simulation of the damage on single-crystal silicon to further explain the generation mechanism of cleavage crack located in the single-crystal silicon surface.The results showed that the temperature in the center of the laser irradiation is the highest in the whole area.Along the axial and radial the temperature decreases gradually.The distribution of temperature mainly tends to material surface area within the laser spot and render the conical distribution.The temperature gradient between spot center and other areas increases with irradiation time, which caused the generation of thermal stress. The material will slip when the shear stress of twelve different slip systems exceed the yield strength of single-crystal silicon.And plastic slip first occurs in the location of the laser spot center along the z axis.The whole slip area appears bowl-shaped distribution when we considerate the interaction of all the types of slip systems.The overlap between different slips act as perpendicular cleavage cracks along the [110] and the direction. Keywords millisecond laser single-crystal silicon damage crystal plasticity FEM 目 次 1 引言 1 1.1 研究背景与意义 1 1.2 激光与硅材料相互作用的研究现状 2 1.3 本文的主要研究工作 3 2 晶体塑性滑移的基本理论 4 2.1 晶体塑性理论基础 4 2.2 晶体塑性变形运动学 7 2.3 晶体塑性本构关系 10 2.4 单晶应变硬化规律 11 3 温度场的数值模拟与分析 13 3.1 温度场的有限元模型 13 3.2 温度场的计算结果与分析 15 3.3 本章小结 17 (责任编辑：qin) |