アルミニウム合金の二段多重変動荷重下での疲労き裂進展挙動 : 変動荷重レベルがともに疲労き裂進展曲線の第II領域にある場合(<小特集>衝撃小特集)

概要

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Aluminum alloy (A2017-T3) compact tension specimens were tested under repeated two-step load conditions, and the crack growth rate and crack closure behavior were observed. The higher and lower stress levels, K_H and K_L, were selected in the region II of the crack growth rate curve of the material obtained by ΔK increasing tests. It was found that the crack growth rate da/dN and crack opening stress intensity K_<op> were affected by the stress cycle ratio K_L/N_H; namely, da/dN was decreased and K_<op> was raised by the increase of N_L/N_H. The estimation of the crack growth rate for lower stress level K_L by the linear commulative law shows that the estimated relation of (da/dN)_L versus (K_<eff>)_L was in better agreement with the fundamental crack growth rate curve when the crack closure only in the repetition of K_L was taken into account, than when the closure at both stress levels of K_H and K_L were considered.
社団法人日本材料学会の論文
1987-12-15