Using adaptive inflatable structures (AIS) surrounding a wind turbine tower on the water level is a possibility of effective protection against ship collision. The main purpose of this report is to perform the feasibility study of such inflatable structures. The analysed inflatable structure has the shape of a torus which surrounds the tower on the water level protecting it against ship collisions. Design and dimensions of AIS are determined by tower mass and stiffness. Pressure inside the chambers is adjusted according to the velocity and mass of the approaching ship. In this case the main purpose is to avoid direct collision between the ship and the tower and arising excessive forces and accelerations. By using compressed air one also increase the time of impact and possibly mitigate vibrations of the tower induced by ship collision. Inflatable structure for this application can be made of rubber reinforced with metal rods. This kind of material provides adequate durability for high values of pressure and allows large deformation during impact. Modelling of such structures is based on interaction between solid wall and fluid enclosed inside. The main numerical tool used for calculations is ABAQUS software which utilises Finite Element Method (FEM). ABAQUS/Standard uses implicit scheme of solution and solves equilibrium equations directly on every increment. In contrast, ABAQUS/Explicit advances the solution kinematically in small increments without solving coupled set of equations. This makes the explicit method better suited for fast dynamic or strongly nonlinear problems. ABAQUS/Explicit contains more built-in options for modelling various deployment and flow conditions, but ABAQUS/Standard is found to be better suited for modelling Adaptive Inflatable Structures due to the possibility of using FORTRAN subroutines for the purpose of controlling gas flow during analysis. The wind turbine is reduced to a one and two-dimensional model on the water level. Parametric analysis performed on a one-dimensional model is used to investigate the basic features of the new solution. Then a two-dimensional model is applied for a more precise FEM modelling of the ship collision with inflatable structure. Performed feasibility study proves that inflatable structures can protect wind turbine tower and ship against serious damages.
Adaptive Inflatable Structures for protecting wind turbines against ship collisions
Adaptive aufblasbare Struktur zum Schutz von Windturbinen gegen Schiffskollisionen
2006
86 Seiten, Bilder, Tabellen, Quellen
Miscellaneous
English
aufblasbares Bauteil , Druckluft , Druckregelung , Finite-Elemente-Berechnungsprogramm , Kollisionsschutz , Kreiswulst , Machbarkeitsstudie , mathematisches Modell , Methodenvergleich , ortsfeste Plattform , Windturbine , Aufprallenergieabsorptionsvermögen , energieverzehrender Stoßfänger , Aufprallpuffer , Schiff
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