Ti-Ni形状記憶合金コイルばねの熱サイクル定ひずみ疲労における疲労き裂進展挙動

概要

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The fatigue characteristics of Ti-Ni SMA coil springs under cyclic thermal and extension fatigue were investigated. The crack growth behavior and the fracture aspect were observed at several strain levels at three heating temperatures (60,70 and 80℃). The cracks initiated on the inside surface of the coil springs and propagated in a direction almost perpendicular to the direction of maximum principal strain near the crack origin. The relations between crack growth rate (da/dN) and stress intensity factor range (ΔK_σ) and strain intensity factor range (ΔK_c) were found to be almost linear in a bilogarithmic graph. In particular, the da/dN-(ΔK_c) relation in the case of a 60℃ heating temperature was almost same as that in the case of an 80℃ heating temperature.
社団法人日本機械学会の論文
1998-02-25