デジタル画像相関法を用いた板厚の異なる構造用鋼の疲労亀裂伝ぱ挙動評価

抄録

In this paper, fatigue tests using SENT specimens with different thicknesses were carried out to evaluate the effect of plate thickness on the DIC measurements and fatigue crack propagation properties. The fatigue crack propagation rate da/dN of the thin specimen was slower than that of the thicker specimens. The crack opening/closure behaviors at the arbitrary crack location were evaluated by the crack opening displacement measured by the DIC. The crack opening load P_op was higher with thinner specimens, especially with shorter crack lengths. da/dN was correlated with effective stress intensity factor range ΔK_eff based on the P_op at the fatigue crack tip, but the error increased with thinner plate thicknesses and longer crack lengths. The strain range at the fatigue crack tip measured by DIC showed a good correlation with da/dN, irrespective of the plate thickness and crack length.