The micromechanics study on short fiber reinforced composites was made.
1. Microfractures and Nonlinear Behaviors of Short Fiber Reinforced Composites
The 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 Composites
Stress 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.