Modelling and simulations of window attachments for a surface warfare ship

Abstract: In recent years it has been discovered that the window installations on the Visby class corvette are prone to break. The aim of this report is to perform a structural analysis of three different windowinstallations. Thus, to find which window installation minimizes the risk of leaks and cracks in the attachment connecting the window glass and the hull. The three window installations consist of theexisting window installation and one of SAAB Kockums alternative solutions installed in two different ways, with and without an additional damping mass. The model that will be used in the simulationswill consist of a rectangular shaped carbon fibre composite sandwich plate that represents the side structure of the maneuver deck. Furthermore, it will include three windows where only the middlepositioned window will contain the given installation details in order to reduce the complexity of both the modelling and the simulations. Three load cases were simulated in ANSYS Workbench. Thefirst load case called "hogging" consisted of a bending moment along the vertical sides of the model. The second load case called "slamming" consisted of a vertical force pointing upwards along thebottom of the model. Lastly, a torsion load case was simulated. In all load cases the existing window installation were subjected to the largest strains along the inner edges of the attachment. In theslamming load case, the alternative solution without the double damping mass was exposed to least strains around the inner edges of attachment compared to the other window installations. For thehogging and the torsion load case the alternative solution with double damping mass produced least strains around the inner edges of the attachment. But the alternative solution without the doubledamping mass was also able to reduce the strains around the inner edges compared to the existing window installation. In conclusion, the alternative solution without an additional damping mass isin overall minimizing the strains along the inner edges of the attachment in which the most leaks and cracks have been observed. It has especially been efficient in reducing strains in the slammingload case. Even though the window installation with an additional damping mass best withstands hogging and torsion, the slamming load case is the most common scenario. Therefore, the windowinstallation that best withstands the slamming load case should be prioritized. Thus, the alternative window installation without the additional damping mass is the best alternative because it bestwithstands slamming but also reduces the strains along the inner edges compared to the existing window installation in the other load cases.