高温水環境下における樹脂中ガラス繊維の残存強度の予測法の提案

概要

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Mechanical properties of glass fiber reinforced plastics (GFRP) mainly depend on the mechanical properties of the glass fiber, which decreases with stress and corrosion. Thus, the calculation method to predict the residual fiber strength after exposure to stress and corrosion is required. In this paper, constant strain test of single fiber composite (SFC) was conducted in hydrothermal environment (deionized water) at 40°C and 75°C to apply the stress and the hydrothermal aging. The residual fiber strength after constant strain test was evaluated by fiber fragmentation test. Besides, the residual strength of glass fiber was predicted using subcritical crack growth model. In the subcritical crack growth model, the surface flaw on the fiber surface which arises while manufacturing was assumed as an ideal crack. The crack growth rate was expressed by the combination of Paris law and Arrhenius model, and the strain history of constant strain test was integrated into the calculation. The residual strength of the glass fiber was calculated based on the fracture mechanics discussing the crack length. The predicted results of the fiber strength showed good agreement with the experimental data at various experimental conditions and the validity of the proposed model was ascertained in this paper.