Abstract
It is shown that in proof testing of ceramic components, a phenomenon that strength after proof testing, Sf, depends quite sensitively on initial strength, Si appears under certain conditions. For example, a slight difference of Si only by 0.005MPa results in a large difference of Sf by some 400MPa. The reason and conditions for this phenomenon to appear are investigated theoretically. It is shown that this phenomenon appears when the unloading stress rate is considerably low and the crack growth exponent n is large as in ceramics. A practical aspect of the phenomenon is also discussed.
