中文摘要：

针对颗粒为椭球形状并且随机分布的多相复合材料给出了三维情形下的计算机模拟方法，并对此复杂区域提供了一种四面体网格快速生成算法。此方法的基本思想：首先是根据材料的要求，给出随机颗粒材料的计算机模拟，然后对模拟后的颗粒边界初始化，得到一些初始剖分点，并给出剖分区域的初始网格（正四面体），接着把颗粒的初始边界点投入到剖分区域中，替换区域中靠此点近的点，并且采用加点寻找边界的方法和修正初始点方法来解决四面体穿刺边界问题，从而得到整个区域的四面体网格。最后用实例说明了算法的有效性。

英文摘要：

In this paper, the numerical simulation method for the composite material with large numbers of grains randomly distributed in three dimensional domains and the algorithm to auto-generate tetrahedron meshes in three dimensional domains are presented. Firstly, based on the properties of the composite material with grains randomly distributed and the simulating technique of the ellipses covering the grain of any shape, the simulation method for the composite material with a large number of random grain el- lipses in three dimensional domains is given in section 2, and then the algorithm to obtain the original boundary points of random grains is described in section 3. Secondly, based on the cubic background meshes to fast search the inserted points and by the techniques to move the background points, one improved algorithm to automatically generate the tetrahedron meshes is established in section 4. Thirdly, some correctional techniques such as adding the points into the boundary of random grains and correcting the original boundary points to keep the properties of the boundary tetrahedron in the grains are introduced. Finally, some examples in three-dimensional domains illustrate that the above algorithm is valid. Finally, the future work of the paper is given. The algorithm can be extended to deal with the materials with cracks, cavities or other polyhedron grains.