Abstract
It is well known that the initial crack growth rate is very high, when notched specimen is loaded by cyclic compressive stress. This reason is estiamted to be a occurrence of crack opening by the existence of a remained tensile stress. Therefore the influence of compressive stress for the crack opening phenomena and for the non-propagating crack was investigated. Used material was Alminum alloy and specimen figure was CT specimen. On the condition of three kinds of stress ratio R (R=0, R=1 and only compressive stress) crack propagation tests were performed. Even when absolute maximum values are same and crack dose not propagate by only tensile stress, there exists non-propagating crack on the condition of R=-1 and only compressive stress. Therefore it is found that non-propagating crack has a close relation to compressive stress.
