ガラス短繊維強化熱硬化性樹脂の破壊靭性評価

抄録

The fracture toughness of glass-fiber-reinforced thermosetting resin, molded by the transfer molding process is measured experimentally. The glass fiber is oriented unidirectionally near the surface of the plate and randomly inside the plate. The specimen is modeled by the two-layer model. The fracture toughness is measured using three-point bending specimens with different thicknesses. They are made by cutting off the surface of the bulk plate. The specimen made of the surface layer shows higher fracture toughness than that made of the central part. Three-dimensional FEM analyses are conducted considering the difference of the fiber orientation. It is found that the existence of the surface layer in the thickness direction has little effect on the fracture toughness, and that in the width direction increases the apparent fracture toughness. Residual stress distributions in the plate are measured by the layer removal method, coupled with the FEM calculation. The effect of residual stress is studied by two-dimensional FEM. It is shown that crack tip stress decreases with residual stress, which agrees with the experimental results qualitatively.