In the first part of this paper a review of a previous work on crack closure mechanisms in compact tension specimens of 7175 T651 aluminum alloy is presented. Results showed that the methods of measurement are responsible for the controversy on Elber's concept. However mechanisms of closure in such a specimen are too complex to conclude on the influence of mechanical parameters on the crack closure effect. Hence, tests have been performed, on the one hand, on thin sheets in order to verify the validity of Elber's concept in plane stress conditions. On the other hand, tests were carried out using tension and bending specimens containing surface or corner flaws, where a plane strain state is predominant. These works have been conducted on a 2124 T351 aluminum alloy. The crack closure mechanism has been found to be the principal parameter that governs the propagation mechanisms whatever parameters are studied, at least when the Paris relation is verified. Parameters such as applied stress, R ratio, stress state, and load variation (overload), have been retained for this study.