エポキシ間異材境界上の疲労き裂伝ぱ特性と接合力の評価

概要

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Strength of the bonded interface is generally low under the loading perpendicular to it. Therefore the investigation on the fatigue strength of the interfase or the fatigue crack growth along the interface seems to be important to use composite materials. In this paper, the fatigue crack growth phenomenon along the interface and the fatigue strength are investigated in detail using epoxy dissimilar plate specimens with various Young's modulus ratios and different bonding strengths. It is found that the fatigue crack growth rate (da/dN) along the interface can be characterized by the apparent stress intensity facter range ΔK_<Iapp> caluculated as the stress intensity factor for a crack in a homogeneous material. The da/dN-ΔK_<Iapp> relations for various composite specimens are independent on Young's modulus ratio and specimen type. Therefore these relations seem to be a measure usefull for the quantitative evaluation of bonding strength of the interfase. Moreover the particular behavior of fatigue strengths of smooth composite specimens can be explained by the da/dN-ΔK_<Iapp> relations along the interface.
1986-04-25