Penerapan Metode Multiple Scales untuk Masalah Galloping pada Mooring Cable FPSO

Abstract

Every object has a natural frequency. When an object gets an external force same with their natural frequency, a resonance will occur. In this study we examined how the dynamic behavior of the mooringcable of Floating Production Storage Offloading (FPSO). The mooring type isCatenary Anchor LegMooring (CALM).What happens with mooringcable if it gets external force with a small frequency but it is so close to the natural frequency of the system. In the case of transmission cable, the phenomenon that describe this event is called the Galloping Phenomenon. The mathematics model of CALM system with a small frequency will be solved using Multiple scales method. The equilibrium point obtained is in the form of a center (stable). For negative, the amplitude value will be positive when the phase is zero (in-phase), at this condition if the initial conditions are chosen close enough to the equilibrium point then the cable will periodically oscillate with a limited phase value. If the initial conditions are selected a little further from the point of equilibrium, it will oscillate with amplitude the initial is the maximum amplitude and its value added of the dependent phase against time.