纳观分形粗糙表面的建模分析

Modeling and Analysis of Fractal Rough Nanoscale Surfaces

采用删除原子法对纳观粗糙表面的建模进行了研究.研究表明:利用含有原子、晶格等信息的标准data文件,根据边界特性删除原子,结合分形理论,可建立出具有分形粗糙特征的纳观模型.由W-M分形函数决定的粗糙表面,以最小的晶面距离作为扫描间距时,易出现含有孤立原子列的不合理结构,为了后续粗糙面纳观摩擦接触模拟分析,可通过傅里叶变换及滤波处理消除孤立的原子列,但滤波处理会导致某些分形特征的消失,通过适当增大滤波器的通带半径,再利用能量最小化的方法优化初始结构,可保留粗糙面原有的分形特征.试验表明,该方法能有效建立与实际表面相符的纳观分形粗糙面数字化表征模型.

Modeling analysis of a fractal rough surface at nanoscale is established by the method of removing atoms. It is found that utilizing the standard data file which contained the information of atom and lattice and removing atoms according to the boundary conditions, a rough surface model with fractal characteristics at nanoscale can be established by considering fractal theory. The rough surface determined by the W-M fractal function was prone to unreasonable structure with isolating atom columns when the atomic lattice constant was used as scanning interval. For a better frictional simulation of rough surfaces in nanoscale by the lammps software, Fourier transform and filtering process were adopted to remove these isolated atom columns. During this process, the fractal characteristics of the rough nanoscale surfaces can be preserved by increasing the pass radius of the filter and optimizing initial structure with the method of minimizing energy. Experiments showed that this method effectively established the fractal rough nanoscale surface which is consistent with the practical surface.