Optimal Design of Wire Sheave Used in Offshore Drilling Operations

This paper presents optimized design geometries of wire sheaves that are used in offshore drilling operations. Seven different design geometries of wire sheaves are considered for this study. The criteria considered in this comparison are utilization ratios of yield and buckling capacities and fatigue life. The constrained used are the self-weight and rotational inertia. The obtained utilization ratios of yield capacity, buckling capacity, and fatigue life against the weight and rotational moment of inertia are finally compared. The comparisons reveal that currently used lightest sheave geometry has very good yield and buckling capacities than all other geometries. But it has high self-weight and rotational inertia. Finally, the web with decreasing thickness which has a lowest rotational inertia is proposed as the most suitable design geometry, if the expected design life is limited to 20 years. Different sheave geometries are also proposed depending on the required design service life.