A Micromechanics Study on Short Fiber Reinforced Composites

对短纤维增强复合材料进行了细观力学研究。短纤维增强复合材料的微断裂和非线性行为首先考虑了短纤维增强塑料、金属和陶瓷的损伤形成机制，并建立了模型以模拟其断裂行为。通过计算模拟，对短纤维增强复合材料的承载能力进行了预测。还详细考察了纤维取向、纤维几何形状和纤维-基体界面条件对断裂能的影响。短句来源短纤维增强SMC复合材料应力腐蚀裂纹的扩展速率对玻璃短纤维增强SMC复合材料在酸性环境下的压紧拉伸试样进行了应力腐蚀裂纹试验。然后验证了裂纹扩展速率da/dt与裂纹尖端应力强度因子KAPPA的近似表达式为da/dt=ALPHA^m，其中A和m为常数。从细观力学的角度考察了这种关系，定量地阐明了酸浓度、温度和纤维体积分数对繁殖速率的影响。采用三维边界元法对玻璃纤维应力腐蚀裂纹的扩展行为进行了数值模拟。

The micromechanics study on short fiber reinforced composites was made.1. Microfractures and Nonlinear Behaviors of Short Fiber Reinforced CompositesThe damage formation mechanism in short fiber reinforced plastics, metal and ceramics was first considered, and was modeled in order to simulate the fracture behaviors. By means of the computational simulation, the load carrying capacity of short fiber reinforced composites was predicted. The influences of fiberorientation, fiber geometry and fiber-matrix interfacial conditions on the fracture energy were also examined in detail.2. Propagation Rate of a Stress Corrosion Crack in Short Fiber Reinforced SMC CompositesStress corrosion crack tests were carried out on compact tension specimens made from a glass short fiber reinforced SMC composite in acid environment. Then, it was verified that the crack propagation rate da/dt is approximately expressed against the stress intensity factor KAPPA at crack tip in the form da/dt=ALPHA^m where A and m are constans. This relationship was examined from the viewpoint of micromechanics, and the influences of concentration of acid, temperature and fiber volume fraction on the propagation rate were clarified quantitatively. Furthermore, the numerical simulation of the extension behavior of the stress corrosion crack in a glass fiber was performed by using the three-dimensional BEM.