The Study Of The Assessment Of Corrosion Fatigue Life For Ships In Service

When thinking of the safety of ships and other marine structures, evaluating their fatigue life is necessary. It is important to evaluate these structures at initial state, but for various reasons, this kind of assessment often can not reflect the real fatigue state of structures. In order to obtain more accurate result of fatigue assessment and assess corrosion fatigue life of ships and marine structures which may have been used for several years, a kind of assessment methods which can work with real-time detection data is required to process the assessment of corrosion fatigue life. This article try to expound a sort of assessment methods to solve this problem.The corrosion factor has a great influence on the strength of structure of the aging ships, so this article sets this as research emphasis, proposes the method of evaluating the damage which is due to corrosion fatigue problem of ships and other structures, with the combination of the theories of Miner Linear cumulative damage and crack initiation. This article sets three points below as research emphasis: firstly, according to the real-time corrosion detection data of hull plates, using the theories of Markov and grey prediction to predict the tendency of corrosion. Secondly,in consideration of the corrosion pits which are prone to appear on the face of the rusty plates, make sure the detection data which can describe the degree of corrosion pits, analysis the influence of detection data on enlargement of the stress and research on the corrosive trends of corrosion pits. Thirdly, at different corrosion enviroment, according to related data, propose a method to definite the related corrosion enviroment factors which are necessary for assessment of corrosion fatigue life of aged ships. On this basis, propose the implementation method of the assessment of corrosion fatigue life of aged ships, set a 11 years-old barge as example to calculate the corrosion fatigue life of one part.In the analysis of the corrosion fatigue life of the barge, using Matlab software to realize the program of improved grey prediction to predict the tendency of corrosion. Using Sesam software to calculate the design wave of the barge and the response of the ship under the design wave. Using Ansys software to calculate the stress concentration factor of the relative place. With all former work combined with the method of the corrosion fatigue assessment, the corrosion fatigue damage of each years will be obtained. This article will have some reference value for the fatigue or corrosion fatigue assessment of ships and other marine structures.