Development of the Centrifugal Pendulum Absorber for the Reduction of Ship Superstructure Vibration

Abstract

This paper deals with the development of a centrifugal pendulum absorber to reduce ship superstructure vibration. The developped absorber has following characteristics. (a) The size is compact and easy to install on superstructure. (b) Vibration of any order caused by engine or propeller can be reduced. (c) Random variations of amplitude and phase can be automatically followed. (d) Any other structures are not excited by the absorber. The authors performed the theoretical analysis of the absorber and carried out the forced vibration experiment of a model structure by a test absorber and it's control system. The conclusions obtained are as follows. (1) This absorber was effective to reduce vibration of the structure as it was predicted by theoretical analysis. From the test of pendulum bearing endurance and control system simulation, we confirm this absorber can be applied to an actual ship. (2) In the absorber, pendulum tuning is most important. Mass ratio decides the permissible tuning error value. Small mass ratio requests the accurate tuning control. Resonance caused by tuning error larger than permissible value makes the absorber ineffective. (3) From the experiment, the amplitude of the structure was constant and independent from exciting force when pendulum tuning was perfect. This can be explained by the theoretical analysis of Coulomb damping acting on pendulums.