Comparison of Different Methods for Ultimate Strength Assessment of Ship Model in Bending

Abstract The nonlinear Finite Element Method (FEM) as well as the Idealized Structural Unit Method (ISUM) are applied to perform progressive collapse analyses for a 1/3-scale steel frigate model in bending. For the load case of pure vertical bending (sagging), the numerical results are validated against experimental data. Both numerical models are explained in detail considering the initial imperfections of the stiffeners and the attached plating. An elastic-perfectly plastic material model is applied. Displacement controlled nonlinear analyses are performed in framework of ISUM and FEM by using the full Newton-Raphson scheme an incremental iterative solution approach. Furthermore, Smith’s method is applied to determine the progressive collapse behavior of the 1/3-scale frigate model in bending. Smith’s method based calculations are performed under consideration of scantlings and rule based load-end shortening curves for all the structural components. The different numerical approaches are applied to determine the progressive collapse behavior of the frigate model in vertical, horizontal and biaxial bending. The ultimate strength results are assessed successfully and compared to each other.