Mode I and Mode II Stress Intensity Factors Based on Crack Opening and Sliding Displacements

Abstract

It is necessary to study crack opening and sliding discontinuous displacement behavior under mixed-mode conditions because parts or structures of a machine with a crack maybe subject to stress from various directions. In this study ,therefore, using the cracks with different slant angle, which are made in circle stress of modeⅠwith stress ratio of R=0, the opening and sliding discontinuous displacements are measured ,so that modeⅠand mode Ⅱ stress intensity factors (KⅠ)mes and (KⅡ)mes at the crack tip are calculated. As a result, the measured stress intensity factors value of (KⅠ)mes from the fatigue crack with the slant angle β=60 deg. is smaller than the theoretical one (KⅠ). But for mode Ⅱ,(KⅡ)mes is about the same with (KⅡ). On the other hand, for the fatigue cracks with smaller slant angle β=45 deg.,(KⅡ)mes declined because of the crack-surface contact while (KⅠ)mes reduced.