纳微米双相颗粒增强陶瓷基复合材料力学性能的数值模拟

The simulation of the mechanical properties of ceramic-based composites reinforced with nano-micro particles

以包晶型(纳米颗粒包围微米颗粒)和内晶型(纳米颗粒嵌于微米颗粒中)2种分布状态的特征体积单元为研究对象,利用整体-局部均质化方法从数值分析的角度计算了复相陶瓷材料中纳米颗粒与微米颗粒的排列方式、体积比、粒径比、界面特征等纳微观结构特性对纳微米颗粒增强陶瓷基复合材料有效弹性模量的影响。结果表明纳微米颗粒呈包晶型分布状态时,随体积百分比的增加,有效模量增大较为显著;与矩形特征体积单元相比,六边形情况估算有效弹性模量偏高;纳微米颗粒粒径比越小,颗粒分布越均匀,有效弹性模量越大;微观颗粒与基体间的界面损伤比纳观颗粒与基体的界面损伤更易于导致材料的有效刚度降低。从晶粒细化特征及显微结构等因素解释合理的纳微观复相颗粒分布对陶瓷基复合材料的有效弹性模量的改善效应。

The global-local homogenization method with precise period boundary conditions is applied to analyze the factors to affect the mechanical properties of ceramic composites reinforced by spherical nano-micro particles. The sizes of the particles vary from micro-to nano-scale. Two kinds of representative volume elements （RVE） are applied to describe different arrays of nano-micro particles. One is the enwrapping array in which the micro-particles are enwrapped by some nanoparticles, and the other is the nesting array in which the nano-particles are nested within the microscopic particles. The numerical simulation is performed with the changes of radius ratios of nano-micro particles, volume fractions and the interracial properties. The results show that the low radius ratios of nano-micro particles produce a larger effective elastic modulus for its more uniform dispersion, and the interracial damage between micro particles and matrix deteriorates the effective elastic modulus more serious than the interracial damage between nano-particles and matrix, and the hexagon RVE with nesting array can make an overestimate for effective elastic modulus of ceramic composites. It shows that it is significant to improve the mechanical properties of ceramic materials by mixing some nano- and micro-particles into the matrix with good designed interface properties from the viewpoints of nano-microscopic crystal structure.