Study On Dynamics Of Single-point Mooring Systems

The single-point mooring system (SPMS) is one of the most important types forfixing ocean structure in the field of marine engineering, ocean observations, andaquaculture. Single-point mooring systems have the advantages of simple structure,good directivity, and low cost. However, under the harsh sea condition SPM systemsoften suffer complex and serious loads in the process of deployment, operation andrecovery. In this thesis, dynamic analysis of SPMS is carried out to deeply study themechanism of dynamics, predict the performance of mooring systems, and providethe theory basis for the security of systems’ integrity and reliability.A polygon approximation method based on lumped mass has been applied tostudy the statics of the single-point mooring system. By using lumped mass modeland iterative approach, the attitude and tension distribution of the system are obtainedby a linear interpolation method.Dynamic model of SPMS is also developed taking into account the nonlinearfactors of flexibility of the cable/chain and the effects of fluid inertia forces. Motionof SPMS is simulated during deployment by using numerical technique in timedomain. The influences of current, mass and initial positions on dynamic response arealso given. Dynamic response of SPMS under regular wave excitation is analyzed,and the static profiles of SPMS are also analyzed based on the dynamic model.A program package on dynamic response of SPMS is developed on the basis ofdynamics analysis. Through it parameters can be inputted conveniently byuser-friendly interface, and the motion curves, tables and animation of response canbe shown intuitively in the software.