颗粒和纤维混杂增强复合材料力学性能的三维有限元模拟

3D FEM simulation of mechanical property of composites reinforced by both particles and fibers

为了研究原位合成TiB纤维和TiC颗粒混杂增强的钛基复合材料的力学性能与微观结构的关系,根据其微观结构特点,并基于随机序列吸附(RSA:Random Sequential Adsorption)方法,提出了短纤维和颗粒混杂增强的三维有限元模型。该模型可以生成位置及取向随机分布的多纤维多颗粒的代表体积单元,同时纤维的长径比、取向分布规律可以任意调整,适合各种不同的混杂增强复合材料微观结构的模拟。对比实验测试结果,证明该模型对混杂增强的复合材料的模拟较为精确。模拟结果显示:在纤维状增强体中,平行于加载方向的增强体承载了最大的应力,而与加载方向约呈45°角的增强体承受的应力最小;颗粒状增强体承受的应力相比平行于加载方向的纤维状增强体要小很多;基体中应力在加载方向上靠很近的增强体之间较高。

In order to investigate the relation between mechanical property and microstructure of in-situ synthesized Ti matrix composites reinforced by both short-fiber-like TiB and particle-like TiC, a 3D cell model was developed on the basis of the RSA （Random Sequential Adsorption） method, according to observed microstructures. This model can be used to generate a multi-inclusion cell with both randomly distributed short-fiber-like and the particle-like reinforcements, and that the aspect ratio of short-fiber-like reinforcements and the distribution rule can be arbitrarily set. While compared with the experimental results, the simulation results obtained using this model are relatively accurate. The results show that： in the short-fiber-like reinforcements, the ones parallel to the direction of the applied stress bear the most stress, while the ones at an angle of about 45 degrees with the direction of the applied stress bear the least. The particle-like ones bear much less stress than the short-fiber-like ones parallel to the direction of the applied stress. The stress in the matrix is higher in the local where the reinforcements are compact along the direction of the applied stress.