The Research Of The Ultimate Strength Test Technology Of Ship Structures

Ship model test technology is significant for the ship ultimate strength research.The current common ultimate strength model tests are divided into similar model test and box girder model test.The advantages of the former are direct reaction of the hull ultimate strength,but accompanied by the disadvantages like large size,long test period and high cost.The box girder model can effectively control the test cost and test cycle,but do not reflect the real ship ultimate strength.Now in the ultimate strength test,it is necessary to reduce test costs,shorten the test period and to improve the accuracy of test results.In this paper,based on the design technology of the test model and the advantages of similar model and the box girder model,the method of the model design of hull ultimate strength is presented.The ultimate strength test model is designed and the model test is conducted.Firstly,the theoretical calculation method of stiffened plate and hull girder ultimate strength were studied.Computational formula of the stiffened plate failure modes and failure stress is in detail given,and a FORTRAN program is prepared accordingly.The principle of the calculation of the hull girder ultimate strength by progressive collapse method and nonlinear finite element method are illustrated.And accordingly the hull girder ultimate strength is calculated with the use of linear elastic law,progressive collapse method and nonlinear finite element method.Secondly,the derivation of similarity theory and similarity criteria is described.The application and limitations of similarity theory in the hull girder ultimate strength model test are clarified.Thirdly,three small-scale test models which can be used to predict the ultimate strength of the hull girder are presented.Using the nonlinear finite element method,the stiffened plate compression model,restructured box girder model and the simplified model were analyzed.It shows that the results of the two box-girder model of the hull girder ultimate strength are close to the ones of the real ship hull.Finally,an ultimate strength test is implemented according to the design of the restructured box girder model.The test results demonstrate the reasonableness of the proposed small-scale model.