Jacket platforms are inevitably undergoing the environmental loads such as wind, waves, current, ice and earthquake etc., which will induce continuous vibration of the platforms. The vibration, on one hand, will cause fatigue damage, decreasing the platform’s reliability; on the other hand, the excessive vibration can’t satisfy the basic psychological requirements of the personnel. In order to reduce the excessive vibration of jacket platforms effectively, many control strategy and control equipments are proposed and studied. In the present study, a model experiment is designed to investigate the effectiveness of semi-active vibration control system with Magnetorheological (MR) Damper. A typical jacket offshore platform in Mexico Gulf is selected as experimental prototype. The model of the jacket platform is designed based on dynamical similarity criterion by the scale of 1:50. Furthermore, the optimal semi-active system of MR damper is designed by fuzzy control theory. In order to investigate the control effect of MR damper on the jacket platform under regular and random wave state, several model experiment load cases are performed. The experimental results show that the MR system designed by fuzzy theory can reduce the vibration of the platform effectively and in the same time the control effect is stable.
Characteristics and Dynamic Modeling of MR Damper for Semi-active Vibration Control
