Theory And Software Developing For Stability Curve Of Decomposing-Composing Structure

With the expanding of exploitation of ocean resources and the development of the technology of offshore engineering, both the type and the shape of floating structures increasingly become diverse and complicated. On the other hand, with the trend of moving towards deeper seas in severer environmental conditions, their stability has been more concerned.From this point of view, in order to find a new method of stability calculation which is applicable to all kinds of floating structures, the concept of Decomposing-Composing Structure is brought forward. Considering most structures having arbitrary and multiple shapes, once being decomposed, their hull geometry definition and geometric properties calculation of immersed hull will become easier. The whole structure is considered as a collection of all compartments, and each compartment contributes to the hydrostatic properties of the whole structure.The whole structure is decomposed into two kinds of compartments: primitive ones and arbitrary ones, both their definitions of hull geometry and establishments of local coordinate systems are introduced respectively. The equation of water plane in coordinate systems of both structure and compartments are deducted, based on which the floating parameters of each compartment can be represented by the ones of the whole structure. Two series of floating parameters are defined in this thesis, one includes average draft, heel angle and pitch angle, namely, T, θ,φ the other includes average draft, axis direction angle and inclining angle, namely, T, ω,ζ.The mathematical relation between the two series is presented.With reference to conventional ship, the calculation of intersection between each compartment and water plane is introduced, as well as the calculation of relevant geometric properties. After that, by summing up these properties of all compartments the hydrostatic particulars of the whole structure can be worked out. Considering the arbitrary direction of inclining axis, the mathematical formulation of stability arm in three dimension is presented, and the concept of the Curve of Minimum Stability Arm in three dimension is brought forward. The stability curve of the Decomposing-Composing Structure is calculated by the theory of optimization. .Basis on above method, using Visual Basic Programming language, the stability calculation software for floating structures SCMFS is developed. Its accuracy and availability is tested by two examples.