ATENA Conferences System, NAV 2012 17th International Conference on Ships and Shipping Research

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Structural optimization of innovative rudder and flap for HSC
Antonio Giallanza, Giuseppe Marannano, Antonino Pasta

Last modified: 2012-09-29

Abstract


Currently, the systems of directional and stability control (rudders and flaps) of high speed craft are made by steel box-shaped elements.
This is mainly caused by the high hydrodynamic stresses applied on these elements due to the high cruising speed of HSC.
In order to reduce the weight of these elements and to increase the resistance to external corrosive action, innovative manufacturing technologies and new materials are studied.
In this paper,  innovative hybrid steel-composite rudder and flap are presented to use in high speed craft.
The stiffness and strength, in operating conditions, are guaranteed by material typologies used and by structural  layout of the elements.
Preliminarily, the paper analyzes the possibility to realize, also, the shaft of the rudder and flaps with composite materials instead of traditional stainless steel.
However, it is planned to perform a detailed study of the joint between the body of rudder/flap, made of composite, and the shaft in order to ensure the transmission of the torque due to the hydrodynamic forces that occur at a cruising speed close to 40 kts.
Preliminarily, CFD analyses are performed in order to establish pressure forces at different hydrofoil waterplanes.
The project involves the use of  horizontal stiffeners made in composite materials using special devices to be connected to the shaft.
The horizontal stiffeners of the rudder  are separated by a core of expandable, medium-density polyurethane foam.
The composite skin is made by a unidirectional material in order to create a quasi-isotropic laminate, that is tightly wrapped around the foam core.
Finally, the paper shows a cost-benefit analysis on the use of innovative materials for the construction of rudders and flaps for HSC.


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