短纤维复合材料的压缩强度

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...

Compressive Strength of a Short-fiber-reinforced Composite

The internal stresses in a composite obtained by a micromechanics theory are homogenized quantities. They must be converted into true values before a failure assessment and strength prediction can be made. While the theories for obtaining all of the other directional true stresses have already been established, only the true stress of the matrix in the short fiber reinforced composite (SFRC) under a longitudinal compression is not known. The matrix true stress is obtained by multiplying its homogenized counterpart with the stress concentration factor (SCF). The stress field in the matrix of the SFRC subjected to a longitudinal compression is determined elastically, and is used to derive the longitudinal SCF of the matrix in the composite. Different from definition of the other directional SCFs, a longitudinal SCF of the SFRC must be obtained by subdividing its RVE (representative volume element) into three segments, i.e., two end plus a central ones, so that we can obtain a SCF applicable to any fiber aspect ratio. The homogenized stresses of the fiber and matrix are calculated by Bridging Model. And the compressive strength of a SFRC with any aspect ratio can be predicted easily. Only the geometrical and mechanical properties of the constituent materials are required. The predicted results are in good agreement with the experimental values, the efficiency of the theory established in this paper is finally verified.