Multiobjective Reliability-Based Design of Ship Structures Subjected to Fatigue Damage and Compressive Collapse

Abstract

This work deals with the reliability-based design and optimization of ship structural components subjected to stochastic loads and accounting for the local fatigue damage and buckling and ultimate global strength of the ship hull. The multi-objective structural optimization is performed in minimizing the component net-section area, lateral deflection, and fatigue damage, avoiding local buckling. The probability of compressive collapse and fatigue damage of the ship hull and associated cost is used as a base to define the best design solution. The Pareto frontier solutions, calculated by the non-dominated sorting genetic algorithm (NSGA-II), are employed in defining the feasible solutions of the design variables. The first-order reliability method (FORM) is employed to estimate the Beta reliability index based on the topology of the structural component as a part of the Pareto frontier solutions. Comparing with the original design solution, the optimized section of the identified best design solution area decreased by 9%.