| The scope of this thesis is to investigate robust methods of FEA to evaluate non-linear lower bound limit load estimates of ship type structures. The robust methods used in this thesis include the r-node method, Progressive Modulus Reduction (PMR) method, and the malpha method. The results of each technique are compared to the results of full non-linear finite element analysis, analytical solutions and lab test data where available. The structures modelled in this thesis included a rectangular indeterminate beam, three types of mainframe stiffeners (flat bar, angle and tee), a flat bar stiffened panel and an Arctic icebreaker grillage.;The basis of the r-node method is the identification of redistribution nodes or r-nodes within a structure, which are essentially load-controlled locations.;The malpha method was developed in an attempt to improve lower bound estimates of limit loads, making use of just two linear elastic analyses.;The Progressive Modulus Reduction (PMR) method, which is an extension of the elastic compensation method, systematically adjusts or reduces the moduli of the pseudo-elastic stressed elements of a structure to synthesise the growth of the yield zone. (Abstract shortened by UMI.). |
