Design and analysis of T-joints for fiberglass reinforced plastic ship structures

Angle joints, also named T-joints, used for structural connection of fiberglass bulkheads and decks together or to the ship's shell, have been accomplished by means of boundary angles featuring great thickness and a minimum fillet radius, so that the joints could resist shock loads produced by underwater explosions. IZAR (former Bazan) and the University of Zaragoza have carried out the development of calculations, tools, as well as design and qualification of a new set of T-joints, featuring a large fillet radius and low thickness boundary angle. These joints are lighter easier to produce, more resistant and tougher than the former ones. This paper describes the process of qualification and assessment of the joint's behavior, based on destructive full-scale tests, which were supported by FE modeling and calculations. This research could allow the designer to design and predict the behavior of any desired new joint. For full consistency of the modeling and calculations, the joint failure mechanism and the Point of initiation of failure have been obtained by means of additional acoustic emission tests.