The post-buckling behavior of composite ships' stiffened plate panels has been studied. In this study, the average strain-average stress curves for these panels are derived using progressive failure method as well as nonlinear finite element method. The boundary conditions are appropriate for the continuous plate panels used in shipbuilding. The effects of the aspect ratio, initial geometrical imperfection and stiffener size on the post-buckling of these stiffened panels are evaluated.
KeywordsProgressive failure analysis, hat stiffened plate panel, initial imperfection, Finite Element Method (FEM).Parametric study on average stress-average strain curve of composite stiffened plates using progressive failure method
This paper describes an extended formulation for the coupled beam method (CBM). The method is originally developed for elastic bending response analysis of passenger ships with large multi-deck superstructures. The extension is mainly performed to enable the available method in order to study elastic bending behaviour of ships fitted with superstructures of any sizes and locations. Finite element method (FEM) is applied for solving the equilibrium equations. Both hull and superstructure of the ship are modelled using beam elements. The connection between beam elements representing hull and superstructure is made using specially developed spring box elements. The accuracy of the extended method is demonstrated using an available experimental result. Then, two simplified structures, one representing a ship with a short superstructure and the other one representing a ship with a long superstructure, are analysed in order to validate the extended coupled beam method against the finite element method. In spite of some existing simplifications in the extended formulation, it is very effective in the early stages of ship structural design owing to its advantageous capability of rapid estimation of the longitudinal stress distributions along the height of ships at different stations.
This work explores the postbuckling behavior of a marine stiffened composite plate in the presence of initial imperfections. The imperfection shapes are derived from buckling mode shapes and their combinations. Thereafter, these imperfection shapes are applied to the model, and nonlinear large deflection finite element and progressive failure analyses are performed in ANSYS 18.2 software. The Hashin failure criterion is employed to model the progressive failure in the stiffened composite plate. The effect of the initial geometric imperfection on the stiffened composite plate is investigated by considering various imperfection patterns and magnitudes. Results show that when the magnitude of the imperfection is 20 mm, the ultimate strength of the stiffened composite plate decreases by 31%. Moreover, global imperfection shapes are found to be fundamental in determining the ultimate strength of stiffened composite plates and their postbuckling.
Article Highlights• The effect of initial geometric imperfection mode shapes and magnitude on the ultimate strength of the stiffened composite panels are studied.• The 11 th first buckling mode shapes and a series of combinations of them are assumed as initial geometric imperfections.• The postbuckling and damage are modeled using the progressive damage method and nonlinear finite element method.
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