モードI繰返し荷重を受けるCFRPの層間き裂進展に及ぼす応力比の影響

概要

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Growth behavior of mode I interlaminar cracks in a unidirectional carbon/epoxy laminate, Toray T800H/#3631, was studied under cyclic loading at different stress ratios. Under a constant value of the applied stress intensity range, ΔΚ_<Iap> the crack propagation rate decreased with the crack extension due to crack-tip shielding by fiber bridging. The crack propagation rate was expressed by a power function of the maximum value of the crack-tip stress intensity factor: da/dN=C_0(Κ_<Itip, max>/Κ_<Ic>)^n, where C_0 and fracture toughness Κ_<Ic> are the material constants, while the exponent n strongly depends on the stress ratio. The reduction rate in Κ_Itip due to fiber bridging was determined only by the crack extension Δa, but not by the applied load or the stress ratio. The upper bound of the crack propagation rate can be estimated from the scatter of fracture toughness and the fiber-bridging effect of materials. Change in load amplitude has no influence on either the da/dN-Κ_<Itip>max relation nor the reduction rate in Κ_<Itip.>
社団法人日本材料学会の論文
1995-07-15