Development of simplified limit analysis techniques and their application to ship structure components

Mahmood, Sakib Lutful (2010) Development of simplified limit analysis techniques and their application to ship structure components. Masters thesis, Memorial University of Newfoundland.

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Abstract

In this thesis, the mα - tangent method is implemented in conjunction with elastic modulus adjustment procedure (EMAP) and an algorithm has been proposed for limit load estimation. This technique is applied to a number of ship structure components possessing different kinematic redundancies. By specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible stress and strain distributions are generated, and both lower and upper bound limit load multipliers are obtained. Utilizing the lower and upper bound multipliers, accurate limit loads of ship structure components are then determined using the mα - tangent method. Furthermore, a reference volume correction for regions of peak stresses is incorporated to ensure lower bound limit loads in all the linear elastic iterations. Results are compared with the inelastic finite element results and available analytical solutions. -- Lower bound limit loads for ship structure components are also determined based on a single linear elastic finite element analysis by invoking the concept of kinematically active reference volume in conjunction with the mα -tangent method. The method enables rapid determination of lower bound limit loads for ship structure components by taking their kinematically inactive volume into consideration. This method is applied to a number of ship structure components possessing different percentages of inactive volume. Results are compared with the corresponding inelastic finite element results, and available analytical solutions.

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