2003 年 69 巻 683 号 p. 1088-1093
The stress measurement method using an electrodeposited copper foil with microcircular holes has been developed to measure the cyclic biaxial stress. However, as shearing stress amplitude controls the phenomenon of grown grain occurrence, which is the principle of this method, the static mean stress acting on the elements cannot be measured only using this phenomenon. So the propagation of fatigue cracks from the periphery of microcircular holes are examined to measure mean stress. In this report, temperature and frequency, which affect the crack propagation mainly, are kept constant. And the effect of mean stress on fatigue crack propagation is investigated. Namely, using copper foil and nickel foil, fatigue crack lengths are measured under various combinations of stress amplitude and mean stress, and the basic equations connecting the crack propagation rate, stress amplitude, and mean stress are presented.