Application of crack-tip-strain loop to fatigue-crack propagation

摘要

Cyclic strain at the tip zone of a fatigue crack could be measured continuously by the fine-grating method. At one cycle of fatigue, the loop between strain at the crack tip and applied load was called by the authors the ‘crack-tip-strain loop’ (CTS loop). The CTS loop, which was thought to imply keys of the crack-growth problems, was applied to the fatigue-crack propagation. ΔKeffTwas defined from the stress (or load) range of CTS loop as one corrected parameter of ΔK. Moreover, cyclic crack-tip-strain range,$$Delta _{varepsilon ^{rm T} }$$, from the strain range of CTS loop was proposed as one possible parameter for fatigue-crack propag