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Abstract: In this paper, numerical results of a drop weight impact test examining the dynamic response of a clamped steel beams struck transversely at the centre by a mass with a rectangular indenter are presented. The numerical simulation showed that the results are very sensitive to the way in which the supports are modelled and thus this paper studies the modelling of the structural supports used to clamp the specimen beam in the experiment. The first approach simplifies the structural support as boundary condition on the nodes; the second model represents the entire support as the real approximation; the last approach uses simplified support plate model acting with the beam to simulate the experimental set up. The complete force–displacement curve is used to compare the plastic deformation of the impacted beams, thus the best approximation is selected for further calculations. The finite element model was performed using the LS-DYNA non-linear, dynamic finite element software. The numerical calculations can predict accurately the response of deflections, forces and absorbed energies, when proper boundary conditions are applied, in this case with shell elements representing the support plates. [Copyright &y& Elsevier]

Abstract: This paper presents a numerical simulation and simplified methods for estimating the residual strength of a damaged double bottom. A typical double-bottom structure from a shuttle tanker was modelled. The structure was idealised to a small degree. Imperfections were introduced to the whole structure according to design rules. The most severe situation of the fully loaded condition was investigated. Hull girder bending was considered. Damage was caused by a variety of indenters that were specially designed to obtain a desired damage profile. A total of 16 numerical-calculation cases were investigated using the explicit commercial code LS-DYNA 971. A simplified method was derived. This method includes elastic plus rigid-plastic analyses of a 3-span, single-stiffener model. Unlike Smith''s method, the present approach takes damaged stiffened panels into account in the residual strength assessment. The elastic and rigid-plastic analyses were combined to provide the load-end shortening curve for the damaged stiffeners. A simplified damage mechanism for the tripping of stiffeners is presented, as is a 3-span single stiffener model with proper boundary conditions. Both the analytical and single stiffener models were used to estimate the residual strength of a damaged double bottom. Both methods were validated with a non-linear, finite-element analysis (NLFEA) simulation carried out using LS-DYNA 971. [Copyright &y& Elsevier]