Research On Ultimate Bearing Capacity And Reliability Of Ship Structure In Corrosive Environment

The ultimate bearing capacity of ship structure is the ability of ship structure to resist various external loads without causing damage and deformation.The ultimate bearing capacity of ship structure is an important index to predict the safety performance of ship structure.Therefore,sufficient attention should be paid to the ultimate bearing capacity of ship structure.In the seawater environment where ships are sailing for a long time,various uncertain random corrosion damage will occur to ships’ structures.Corrosion is an important factor affecting the safety of ships and other Marine structures.Due to the randomness of ship structure corrosion and the diversity of factors affecting ship corrosion,reliability method should be used to study the ultimate bearing capacity of ship structure after corrosion.Based on the finite element calculation,the corrosion model and ultimate bearing capacity of randomly corroded ship structures are studied.The main achievements are as follows:1.Based on the existing corrosion data compilation,the marine environment temperature,oxygen content of sea water and marine environmental factors such as relative humidity are marine corrosion rate of ship structure has certain change,puts forward the consideration of the marine environment temperature,oxygen content of sea water and mathematical model of sea-going steel ships of relative humidity affect the corrosion to further develop the existing corrosion model;2.The influence factors of nonlinear finite element analysis on ultimate bearing capacity of stiffened plates are studied comprehensively.The results show that the ultimate bearing capacity and failure modes of stiffened plates with different model ranges and whether or not material strain hardening is considered are not different,and the main changes of these factors are the postbuckling process of stiffened plates.The lateral pressure significantly reduces the ultimate bearing capacity of the stiffened slab structure and changes the buckling mode when it fails;3.Based on the calculation of random corroded stiffened plate model,a formula for calculating the ultimate strength of stiffened plate after corroding ispresented.Compared with the nominal ocean environment,ocean environment temperature,relative humidity and sea water oxygen content have a significant effect on the ultimate corrosion bearing capacity of ship structures.The ultimate corrosion bearing capacity of stiffened plates and ship beams in the same age follows normal distribution;4.According to the ship stiffened plate and random corrosion of ship hull girder ultimate bearing capacity of the calculation results,by using the JC method,calculate the reliability of ship structure,the results show that the ship structure of ultimate bearing capacity reliability decreases with the increase of age,and the reliability of ship structure is roughly linear relationship,along with the change of vessel failure probability increases with the increase of age increase.Considering the influence of environmental factors,the change of structural reliability and failure probability increases with the increase of ship age.