Dario Boote

On the effective breadth of stiffened platings

Abstract A stiffened plate is one of the principal structural components of the hull. During the design phase it is useful to study this structure considering it as a system consisting of monodimensional elements. Therefore, it is appropriate to identify the plate breadth that collaborates with the stiffener in the simplified calculation. The aim of this work is to investigate the effective breadth, regarding both stiffness and strength. The analysis is performed comparing various numerical solutions supplied by a finite-element program with solutions based on the beam theory. Analytic expressions and graphs, derived from the results of the parametric investigation, are proposed to design this kind of structure.

On the damping loss factor of viscoelastic materials for naval applications

ABSTRACT Viscoelastic materials are used in ship and yacht constructions for floating floors, engine foundations and laminated glass. The contribution of viscoelastic rubbers is related to their capability to withstand and damp airborne and structural borne noise. New regulations have outlined the necessity to perform numerical analysis in the early design stages, when modifications in the structural layout and/or in the insulation plan are more feasible and less expensive for shipyards. The determination of damping loss factor of viscoelastic materials is an open topic in vibro-acoustic engineering; the complexity of their mechanical characterisation could have consequences in terms of unreliable numerical simulations if not validated by experiments. In this paper, a new reliable and simple testing procedure for the determination of damping loss factor for viscoelastic materials is presented; experimental data have been compared with finite element analyses and statistical energy analyses in order to validate the proposed method.

Hull–furniture interaction in the primary response to global loads of a carbon fibre sailing yacht

ABSTRACT High performance sailing yachts are generally designed assuming high local and global loads transmitted by rigs to hull structures. The above-mentioned loading conditions can become critical for large hulls also in terms of displacements when composite materials are used. In this scenario, it is very important to use lightweight and high-performance materials, such as carbon fibres. In fact, also some ‘non structural’ components, such as outfit and furniture, are built in carbon fibres and, therefore, can be considered contributing to the hull local and global strength. The aim of this work is to investigate the contribution level of those ‘non-structural’ components to the hull strength. Two different finite element models of a 94 ft sailing yacht, with and without ‘non structural components’, have been carried out in order to evaluate their contribution to the primary hull response to longitudinal bending moment and dock tuning load.

Stress Analysis of Bulk Carrier Hatch Corners

Owing to the hull structure complexity and severe load conditions, bulk carrier ships are the subject of an intense research activity by Classification Societies and research centres. Many problems affecting this kind of vessel derive from loading and unloading operations, corrosion and fatigue phenomena and, sometimes, the age of the ship. For what the structural strength is concerned, one of the typical failure causes for bulk carriers is represented by high stress concentrations occurring in deck plating close to hatch corners in way of coaming stay. The aim of this work, performed in cooperation by the Registro Italiano Navale (RINA) and the Department of Naval Architecture and Ship Construction of the University of Genova, is to investigate the stress distribution close to hatch corners in a systematic way, in order to determine and quantify the influence of the selected parameters on this phenomenon.Copyright