Structural Optimization for Foil-Strut System of a Hydrofoil Craft

Abstract

For the small weight-critical vessel such as a hydrofoil, profitability or performance is determined almost by the hull weight because the decrease of structural weight allows a direct and corresponding increase in the payload. How to reduce the structural weight of foil-strut system and simultaneouly satisfy the hydrodynamic and structural requirements are indeed an optimization problem. An optimization algorithm has been developed to minimize the weight as the designed objective, at the same time, the hydrodynamic lifting force, the divergent speed of the foil, the limitation of stress level, the maximum deflection and twisting distortion of the system have to be taken into consideration as the constrained conditions. The design parameters considered here are the dimensional factors of the geometrical configuration and the scantling variables of the foil-strut system. The locations of hydrodynamic pressure center and the shear center of foil section are determined by the 2-D wing theory and theory of elasticity for a solid bar with arbitrary section respectively. Finally, the numerical designed results of a t-type foil-strut system of a 3000 tons hydrofoil vessel are illustrated by using the established model.