短纤维复合材料的压缩强度  

Compressive Strength of a Short-fiber-reinforced Composite

作　　者：郭威静 黄争鸣[1] Weijing Guo;Zhengming Huang(School of Aerospace Engineering&Applied Mechanics,Tongji University,Shanghai,200092)

机构地区：[1]同济大学航空航天与力学学院,上海200092

出　　处：《固体力学学报》2022年第1期1-15,共15页Chinese Journal of Solid Mechanics

基　　金：国家自然科学基金项目(11832014,11472192)资助。

摘　　要：细观力学理论得到的复合材料内应力是均值应力,在进行破坏和强度预报前,必须转化到真实值.对于短纤维复合材料,除了轴向压缩真实应力外,基体其它方向真实应力计算已得到解决,等于其均值应力乘以基体应力集中系数.论文基于弹性力学方法得到了短纤维复合材料轴向压缩下基体的应力场,并据此定义基体的轴向压缩应力集中系数.与基体其它方向应力集中系数的定义不同,确定轴向应力集中系数时须将代表性单元分割成三部分,即一个中间部分和两个末端部分,进而获得对任意纤维长径比都适用的基体轴向压缩应力集中系数.纤维和基体的均值应力则由桥联模型解析公式计算.只需提供组分材料的几何和力学性能参数,任意长径比短纤维复合材料的压缩强度皆可方便预测.结果发现,纤维长径比和纤维含量对压缩强度都有较大影响.预报结果与实验值吻合合理,证实了论文所建理论的有效性.The internal stresses in a composite obtained by micromechanics theory are homogenized quantities. They must be converted into true values before a failure assessment and strength prediction can be made. For a short-fiber-reinforced composite(SFRC), all true-stress components of the matrix subjected to other directional loads have already been determined, except for the one under longitudinal compression. The true stress of matrix is obtained by multiplying its homogenized counterpart with the corresponding stress concentration factor(SCF) of the matrix in the composite. In this paper, the stress field in the matrix of an SFRC subjected to a longitudinal compression is determined elastically, and used to derive the longitudinal compressive SCF of the matrix. Different from the definition for other directional SCFs, a longitudinal SCF in the SFRC must be determined by subdividing its representative volume element(RVE) into three segments, i.e., a central segment plus two end ones. The obtained SCF is thus applicable to any fiber aspect ratio. The homogenized stresses of the fiber and the matrix are calculated using the bridging model. And the compressive strength of the SFRC with any fiber aspect ratio can be predicted easily. Only the geometric and mechanical properties of the constituent materials are required. Results showed that the volume fraction and the aspect ratio of the fiber both have significant effects on the compressive strength of an SFRC. The predicted results are in good agreement with the experimental data, verifying the efficiency of the theory established in this paper.

关 键 词：短纤维复合材料 细观力学 应力集中系数 真实应力 压缩强度 

分 类 号：TB33[一般工业技术—材料科学与工程]