Rate of thermal-mechanical fatigue crack propagation was investigated under the condition of in phase thermal strain cycle. Experimental rates of crack propagation were correlated with the cyclic J-integral, dJ, which was estimated from the analytical equation derived by Shih and Hutchinson. The effect of tensile strain rates on the thermal-mechanical fatigue crack propagation was discussed in the light of electron fractography. Further, the thermal-mechanical fatigue life was predicted by integrating the equation of crack propagation and it was compared with the experimental fatigue life obtained by the smooth specimen.The conclusions obtained are as follows ;(1) Rate of thermal-mechanical fatigue crack propagation can be expressed by the following equation,(equation) where C and m are material constants.(2) The part-through crack propagates keeping its aspect ratio constant at 0.36. Its aspect ratio is approximately consistent with the one in which the part-through crack has a uniformly distributed elastic stress intensity factor along its entire front.(3) The ruptured surface is changing from the intergranular fracture to the transgranular fracture as crack growth. Striations are formed on the transgranular fracture surface and their spacings are consistent with the rate of crack propagation.(4) Voids are formed at the grain boundaries in the specimen with increasing tensile strain time.(5) Thermal-mechanical fatigue lives can be predicted approximately by integrating the equation of crack propagation.
雑誌名
長岡技術科学大学研究報告
巻
3
ページ
9 - 17
発行年
1982-02-27
ISSN
0388-5631
書誌レコードID
AN00177120
著者版フラグ
publisher
その他のタイトル
Fracture mechanics study on thermal-mechanical fatigue crack propagation
熱疲労き裂の進展挙動に関する破壊力学的検討
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