Research On Ultimate Strength Of Stiffened Plates With Grooving Corrosion Damage

The buckling strength of hull structure is very important in ship structure design,which is also a hot research topic in the shipbuilding industry.As the basic unit of ship hull structure,the stiffened plate is of great importance in its ultimate strength evaluation.The ship structure is always in the harsh marine environment,it would inevitably be corroded.And grooving corrosion is an important corrosion form leading to structural failure.Groove corrosion is a major corrosion form leading to structural failure.The existence of grooving corrosion will reduce the effective thinning of effective thickness of structures,and promote the generation of fatigue cracks,brittle failure and instability damage.It ultimately reduces the resistance of the hull structure to external loads.Therefore,it is vital to evaluate the strength capacity of these corroded steel structures,in order to ensure the safety during the total expected life cycle.At present,the research results on the ultimate strength of non-corrosive stiffened plates and stiffened plates with pitting corrosion have been relatively perfect.But the research on stiffened plates with grooving corrosion is still in the preliminary stage.In this paper,by using finite element method and experiment,the residual strength of stiffened plates with grooving corrosion damage will be systematically studied.A formula for calculating the residual ultimate strength of stiffened plates with groove corrosion damage is proposed.(1)The basic theory and steps of finite element buckling analysis are described.Analyze the model range,initial defects,boundary conditions and mesh size etc..The correctness of the analysis is determined by comparing with existing research.(2)Analyze the influence of corrosion factors and geometrical factors of stiffened plates on ultimate strength,including: finite element type,groove width,groove depth,groove depth-width ratio,initial flexibility(both plate flexibility and stiffener flexibility)and the number of stiffeners.(3)The parameters that can be used to fit the calculation formula of the ultimate strength reduction factor of stiffened plates are determined.The formula for calculating the ultimate strength of stiffened plates with grooving corrosion damage is fitted by multivariate regression analysis.The goodness of fit test the regression analysis method and its application.(4)Design a set of universal fixture for ultimate strength experiment of stiffened plates,which is suitable for general ultimate strength experiment of stiffened plates.The ultimate strength tests are carried out on non-corrosivestiffened plates and stiffened plates with grooving corrosion damage.At last,the test results are compared with the numerical simulation results to verify the reliability of the part of numerical simulation.In this paper,it is shown that groove width,groove depth and plate flexibility are the main factors affect the ultimate strength reduction factor of stiffened plates with grooving corrosion damage.And grooving corrosion depth has a greater influence on structural performance as compared with with corrosion width for the same volume loss.A formula for calculating the residual ultimate strength is fitted by a large number of numerical calculation results.The ultimate strength test results of the complete stiffened plate and the corroded stiffened plate are compared with the numerical calculation results to verify the reliability of the numerical calculation.