REDUCTION OF MOTIONS OF AN OFFSHORE STRUCTURE IN WAVES

研究了海洋结构物在波浪中运动的减振问题。作用在结构上的波浪力被拍板的反作用力抵消，拍板是结构的一部分。拍板由直流电机主动驱动，电机由作用在拍板上的激振力信号控制。根据水波的辐射和绕射理论，可以计算出拍板的最优振动，并由此确定控制系统的最优传递函数。在试验中，驳船式系泊海洋结构物的横摇运动可减少65%。

A reduction of the motions of an offshore structure in waves is studied. Wave forces acting on the structure are canceled by the reaction of the flapping plates, consisting of a part of the structure. The flapping plates are actively driven by a D.C. motor which is controlled by the signals of the exciting force acting on the flapping plates. Optimum oscillation of the flapping plates could be calculated by the radiation and diffraction theory of water waves, and the optimum transfer function of the control system is also determined from the calculation.To verify the above theory, model tests were conducted in the water tank. 65 % of rolling motions of a barge type offshore structure moored by chains could be reduced in the experiments.