モードII静的および繰返し荷重下におけるCFRP積層板の層間はく離き裂の進展挙動

概要

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Growth behavior of interlaminar cracks in unidirectional carbon/epoxy laminates, Toray T800H/# 3631, was studied under mode II static and cyclic loadings. The end notched flexure (ENF)method and the end loaded split (ELS) method were used for crack growth tests. In static tests, the valtle of mode II interlaminar fracture toughness, K_IIc, was constant and independent of the crack extension, Δa. Under mode II shear loading, there was no increase in crack growth resistance due to fiber bridging, in contrast to the case of mode I crack growth. In cyclic tests by keeping the stress intensity range, ΔK_II, constant, the crack propagation rate was independent of the crack extension, Δa, as in static tests. At the stress ratio between 0. 2 and 0. 6, the crack propagation rate, da/dN, was given by a power function of the stress intensity range, ΔK_II, in the region of rates above 10^-9 m/cycle. The exponent of the power function became larger with increasing stress ratio. Below this region, there exists a threshold value of the stress intensity range, ΔK_IIth, for fatigue crack propagation. The value of ΔK_IIth is independent of the stress ratio.
一般社団法人日本機械学会の論文
1995-03-25