Continuous Damage Deactivation in Modeling of Cycle Fatigue of Engineering Materials

When a material is subjected to a cyclic loading at high values of stress or strain, damage develops together with cyclic plastic strain. This process is often accompanied by damage deactivation characterised by actual state of microcracks, which are generally active under tension and passive under compression. In classical formulation damage deactivation occurs instantly when loading changes sign and consequently leads to non smooth path separating both load ranges. The real materials, however, do not exhibit such bilinear paths. Therefore, the more realistic model based on continuous damage deactivation is proposed, in which microcracks close gradually. In the present paper several applications of continuous damage deactivation in modeling of cycle fatigue of engineering materials such as: AISI 316L stainless steel, aluminum alloy Al-2024, ferritic steel 20MnMoNi55 are demonstrated and compared with experimental results. Detail quantitative and qualitative analysis of obtained solutions confirms necessity and correctness of proposed approach. (C) 2010 Published by Elsevier Ltd.