Corrosion In The Plane Of Generalized Life-cycle Analysis Model

A broad sense holistic life assessment model of national aircraft in corrosive environments was given. The essentially theoretic elements and database sketch map of the model were provided. Some pivotal factors of the model were analyzed by way of experimentation and numerical simulation. In conclusion, the residual life and strength assessment methods of the aircraft in serve through corrosion and corrosion fatigue were proposed.In the experimentation, the corrosion damage, the corrosion fatigue crack nucleation and the growth of LY-12 CZ were investigated. The prior corrosion damages were produced in the exfoliation solution. The experimentation was carried out in the different temperatures of corrosion solution, time of corrosion action and stress to analyze the effects of these factors on the corrosion fatigue character of LY-12 CZ. The conclusions can be drawn: after the pre-corrosion of LY-12 CZ, there are many corrosion pits on the surface of the specimens and intercrystal corrosion, and the cracks nucleate from corrosion pits and grow from these corrosion pits under cyclic loading. In most of cases, the crack nucleation and growth is governed by a dominant corrosion pit, and only a few of specimens are found multiple crack growth. Because of the effects of corrosion, the time of crack nucleation is reduced, and the fatigue life of specimens is reduced significantly too. The temperature of corrosion solution has dramatically influence upon the depth of corrosion pits, so upon the fatigue life of specimens.In the view of theory, the assessment metric of fatigue character of aluminum alloy subjected to corrosion damage were proposed, and that is: the ratio of surface corrosion damage and the average depth of corrosion pits. Making use of finite element method and the AFGROW software, the residual life and strength of the aero aluminum alloy structure through corrosion fatigue were predicted. The prediction results are in agreement with the experimentation data. The preliminary results indicated that the model is a useful tool for life cycle management of aircraft in corrosive environments.