Metodología para combinar fibra de vidrio reforzada con estructuras de acero aplicado a superestructura de buques

Abstract

One of the main objectives of ship design and the building is the optimization of the payload, therefore, the reduction of the structure weight is an important factor. The structural weight of the superstructure on passenger and military ships represents between 25% and 40% of the total ship structural weight. The use of composite material for the construction of the superstructure has allowed a considerable structural weight reduction, however, the dissimilar behavior on the hybrid joint between naval steel deck and the composite panels superstructure is a difficulty presented in this type of construction, for this reason, this research will present a methodology to estimate the scantling of the hybrid joint, the first natural frequency of composite panels with reinforcements and recommendations for combining reinforced fiberglass with steel structures. The scantling of composite laminates with steel stiffeners is based on the macro-structural elastic model, following the formulas proposed by the American Bureau of Shipping-ABS. Then a microstructural study of the critical layer is carried out, as recommended by Lloyd’s Register-LR Society, with some modifications proposed in the present investigation. In order to know the construction benefits of a superstructure built with reinforced fiberglass, three comparative analyses have been carried out that include: Analysis of the structural weight, Global analysis of stresses and Forced Vibration Analysis by propeller excitation. To perform the cost-benefit analysis of the composite materials applied in the superstructure, four material different construction options including fiberglass and steel were studied. For the comparative analysis, the form lines of a 36.80 m passenger yacht built-in 2005, with a naval steel hull and fiberglass superstructure with tubular steel structure, have been taken as a reference. From the analysis, it is concluded that the superstructure built with completely fiberglass material would have a greater benefit in weight reduction. Finally, a study of the possible hybrid joints that can be used between the steel deck and fiberglass superstructure is presented. To select the best hybrid joint proposal, a Finite Elements analysis was carried out to estimate the forces to which the hybrid joint will be subjected, then a critical layer analysis on the laminate is performed and finally, acceptance criteria are checked on interlaminar stresses for shear and normal.