Analysis On The Ultimate Strength Capacity Of The Longitudinal Bending Of The Vessel

Since the ultimate strength capacity of vessels is the important guarantee of their security,the research on the ultimate strength capacity is the crucial component of estimation on thestructure strength of ships. Based on the Smith method and nonlinear finite element method, thispaper researches the design method for models of ships within the field of ultimate strengthcapacity. Furthermore, a method for estimating the ultimate strength of models of ships isdeveloped. The work of this paper mainly includes:1) The Smith Method is introduced and a program based on simplified progressive methodfor calculating the ultimate bending moment is developed using Fortran.2) The features of nonlinear problem are reviewed. Two sorts of nonlinear finite elementmethods—the static method and the quasi-static method—are applied and the results of them arecompared. Nonlinear finite element method is used to simulate the initial defect of the model andthen the ultimate bending moment of structures are calculated.3) The results of Smith method and FEM are compared with the initial bending moment, andthen the advantages and disadvantages of them are discussed.4) The contents and application of the similarity theory are introduced. The directionaldimensional analysis method is applied to get the derivation of similarity criterion for the modeltest of ultimate strength.A quantity of criterions within the model design process are presentedand verified. The design method of distortion model in the ultimate strength test of ships isestablished. For a actual ship, the ultimate strength is estimated based on the results given bydistortion model. Then, through the comparison with the results of the Smith program andnonlinear finite element method, the complete set of scheme is verified to be feasible.