Comparison of strength and damage for notched FRP plates made by injection molding with that from machining

Abstract

The strength and damage for two kinds of notched specimen have been investigated. We used an injection molded specimen (IM specimen) made by injection molding using a metal mold of a notched specimen, and a machined specimen (M specimen) made from plate by machining. The orientation of the fiber near the notch roots in the IM specimen and the M specimen is slightly different. The investigation was accomplished by obtaining experimental data of the static tension and fatigue tests on the notched plate of a short glass fiber-reinforced polycarbonate. To evaluate the damage near the notch root, we measured the luminance distributions by means of a luminance-measuring system with a CCD camera. The stress concentration and the similarity of stress distribution near the notch root of the IM specimen were compared with those of the M specimen. For the two kinds of specimen, for both of which the maximum elastic stress, σ max, and notch-root radius ρ were equal to each other, the strength and the process of damage initiation were similar under static tension. On the other hand, the number of loading cycles to fatigue damage initiation of the M specimen was fewer than that of the IM specimen.