繊維強化ポリカーボネート切欠平板の疲労破損の条件

抄録

Failure of notched FRP plates under static or fatigue loading is governed predominantly by the severity near the notch root. The severity is determined by both stress concentration and similarity of stress distribution near the notch root. In the present paper, a fatigue failure criterion based on the concept of severity near the notch root mentioned above is subjected to further experimental scrutiny. The investigation is accomplished by obtaining experimental data on intermediate notch-root radii specimens of a glass fiber-reinforced polycarbonate in pulsating tension. The process of initiation and growth of fatigue damage near the notch root was measured by means of the luminancemeasuring technique using a CCD camera. Closer observation of the microfracture in the fatigue-damage zone revealed the process of the luminance decline along with the increase of loading cycles. The experimental result shows that the number of cycles at the fatigue damage initiation, N_d was governed predominantly by both notch-root radius ρ and the maximum elastic stress σ_max at the notch root, while it was independent of notch depth. Furthermore, the σ_max has a one-to-one correspondence with the N_d when the size of fatigue-damage zone reached the half value of the notch-root radius ρ. On the basis of the concept of severity near the notch root mentioned above, the experimental results can be explained.