The evolution of nano-cracks in mono-crystalline silicon during three-body polishing was investigated by three-dimension molecular dynamics (MD) simulations and theoretical calculations. Atomic displacement, coordination numbers (CN), temperature and stress during the polishing process are studied in detail. The results show that cracks will close rather than expand in ultraprecision mechanical polishing process. The simulation results show two different ways for crack closure due to different crack inclinations: the coordinated displacement of atoms and the phase transformation filling of atoms. Crack closure will result in significant changes in CN. Furthermore, the crack closure effect is the best at 600 K. The calculation shows an obvious uneven stress distribution along the crack line in the polishing process. In addition, the distribution of the normal stress and shear stress at the lower tip of cracks are related to the mode of closure, indicating that simulation is related to the calculated stresses in theoretical model.

通过三维分子动力学（MD）模拟和理论计算，研究了三体抛光过程中单晶硅中纳米裂纹的演变。详细研究了抛光过程中的原子位移，配位数（CN），温度和应力。结果表明，在超精密机械抛光过程中，裂纹将闭合而不是扩展。仿真结果表明，由于不同的裂纹倾斜度，两种不同的裂纹闭合方式是：原子的协调位移和原子的相变填充。裂纹闭合将导致CN发生重大变化。此外，裂纹闭合效果在600 K时最佳。计算表明在抛光过程中沿裂纹线的应力分布明显不均匀。此外，