Engineering strategies for designing lightweight ship windows

Modern cruise ships employ many insulating glass unit (IGU) type windows around the superstructure for increased passenger experience. The IGUs have become weight-critical structures that require weight optimization for better overall vessel efficiency. The optimization is challenged by the lack of details and accurate design methods in the early design phase, where the window's major parameters are decided. Therefore, this dissertation aims to improve the IGU design framework during the ship's early design phase to determine the glass pane thickness for reduced weight. The analysis methods are called engineering strategies, and they consist of (1) numerical optimization and (2) finite element method (FEM), which includes (3) geometric nonlinearity of the glass panes, (4) shear transfer of laminated glass, and (5) load sharing due to the hermetically sealed cavity. Hence, the thickness determination is more accurate than the typical classification rule-based method and has more design flexibility, such as window shape and boundary conditions. The results show that using such strategies is beneficial, as potential weight savings of up to 50% were found with respect to the classification rules. The findings are more evident for large, thin IGUs of monolithic glass panes. The most important factors affecting the weight and bending behavior were the allowable deflection limit, glass pane thickness configuration, IGU shape, and interlayer stiffness in laminated glass. Based on the results and observations in this dissertation, we can conclude that the proposed engineering strategies offer the ship designers better design principles for thickness determination than those currently in use. This helps to reduce glass weight and accomplish the novel ideas dreamed by the ship owners. However, we must further discuss this matter with the corresponding classification societies as they ensure the ship's safe design. This dissertation can work as a foundation for that discussion.