Analysis Of Nonlinear Dynamics Response Of An Articulated Tower Platform

Articulated Tower Platform (ATP) is the important equipment in thedevelopment of oil and gas in the future, it can be applied to different productionphases, such as the drilling, Single Point Mooring and Loading Terminal and so on.Due to the ATP's structural characteristics and the effect of the ocean environment,the dynamic response of ATP, which is involved the nonlinear structure and load, stillcann't be calculated effectively with the available method. The research of ATP'sdynamic response prediction and complicated dynamical characteristics is the keyproblem in the design of ATP, which has very important theory signification andpratical value of the project.The theory research about wave load and response of motion of compliantarticulated tower platform in deep water were carried through in this paper. Theanalytical model of motion was put forward, with considering the nonlinear restoringmoment and wave load. Taken into account the associated wave and current, thedifferential equation of the platform motion was established.The articulated towerplatform's harmonic and sub/super harmonic resonance response in the waves andcurrent were investigated. The influence of the angle between the current and thewave and the initial conditions on the system and nonlinear behavior of platformunder low frequency wave load were discussed here.The formula of calculating natural frequency of ATP is established throughcalculations and analysis, and the approximate formula for estimating equilibriumlocation of ATP is put forward, the impact of the current, friction coefficient, columndiameter, the unit mass of column and the deck mass on the equilibrium location ofATP is presented. By numerical simulation, the conditions of the harmonic, sub/superharmonic resonance conditions are obtained under the wave and current, and theinfluence of fluid damp C Dand coulomb friction damp μ on the motioncharacteristics of system is explained. The response characteristics in the differentcurrent directions, and the conditions of chaos motion are given by examples.