Unified description of small crack growth rate using Delta CTOD in both HCF and LCF conditions
Miyake Masahiro; Harada Shoji; Kurosima Yosihito; Takahara Masao
Abstract:Uniaxial push-pull High Cycle Fatigue (HCF) tests as well as Low Cycle Fatigue (LCF) tests were conducted on a medium carbon steel under constant stress or strain amplitude. To examine the small crack growth behavior, a small drilled hole of 50 mm in diameter and in depth was introduced on each specimen surface. A fracture mechanics parameter, suitable for characterizing fatigue crack growth rate in both fatigue regions was examined. The results showed that the cyclic crack tip opening displacement range (DCTOD), which can well be correlated with overall cyclic plastic strain range Dep, was a suitable parameter to describe the fatigue crack growth rate in both fatigue regions. Key Words:fatigue, small crack growth law,plastic strain range, DCTOD