微粒子ピーニング処理を施したA7075アルミニウム合金の疲労き裂進展特性

摘要

機械要素の疲労破壊では，表面の微小な欠陥からき裂が 発生•進展して破壊に至る場合がほとんどである.したが つて，表面き裂を対象に進展挙動を調査することは，機械 要素の寿命評価を行う上で重要となる.このような観点か ら，航空機構造材料として用いられている高強度アルミニ ウム合金を対象に，デジタル画像相関法を用いて，表面き 裂の進展挙動が調査されている%Fatigue crack propagation behavior of fine particle peened A7075 aluminum alloy was investigated in this study, first, displacement distributions around the crack tip were measured by a digital image correlation method. Then, the effective stress intensity factor range and crack tip opening stress were calculated based on the displacement distribution. Fine particle peening treatment contributes to suppressing the crack opening especially when the crack length is small. However, the retardation effect gradually decreases with increasing crack length. Moreover, it is cleared that the effective stress intensity factor range dominates the surface crack propagation rate, even when the material is subjected to fine particle peening treatment.