多軸応力下での疲労き裂成長速度におよぼす応力成分相互作用効果

概要

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Multiaxial fatigue tests were carried out to investigate the effect of stress components (Δσ,Δτ,σ_<st.>,τ_<st.>) on fatigue crack growth. The test method was the combined tension and tortion one in phase loading by using thin-walled hollow cylindrical specimens with pre-cracks. The experiments were carried out under the condition of equal equivalent stress amplitude,Δσ_eq=√<σ^2+3Δτ^2> Under the condition of mixed modes,the fatigue crack growth rate increases remarkably with increasing stress ratio. This characteristics is due to the effect of static tensile stress σ_<st.> on στ. In this paper,the effect of static tensile stress was incorporated in the consitutive equation of fatigue crack growth rate under the mixed mode fatigue condition of Δσ and Δτ. Then, the following constitutive equation of fatigue crack growth rate including the effects of Δσ,Δτ,σ_<st.> and τ_<st.> was obtained. db/dN=A(ΔK_<Ib>)^m A=(A_R=0)^<1/r^*> r^*={^1+(σ_<st.>/Δτ)^1/2 /7(Region IIa) _1 (Region IIb) A_<R-0>-{^2.16×10^<-5>×0.230^m (Region IIa) _3.64×10^<-5>×0.147^m (Region IIb) m={^f(σ_2/σ_1) (Region IIa) _g(σ_2/σ_1) (Region IIb)
社団法人日本材料学会の論文
1990-08-15