11. Vibration Control of Superstructure of Ships by Means of a Dynamic Vibration Absorber with Adjustable Natural Frequency

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概要

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• The reduction of superstructure vibration is essential for securing comfortable accommodation space and for preventing damage to delicate equipment in ships. Superstructure vibration is divided into three categories. The first is a local vibration where decks and walls vibrate locally. The second is a fore-aft vibration of the superstructure where the entire superstructure vibrates in the fore and aft direction at its resonant frequency. And the third is a vibration which is caused by hull girder vibrations. The prevention of fore-aft vibration is the most, important, because the measures against it are difficult and expensive after delivery. The authors have developed a dynamic vibration absorber of which the natural frequency can be controlled by adjusting the location of the mass. The reduction of the superstructure fore-aft vibration by means of a dynamic vibration absorber were studied, and are presented in this paper. Scale model testes and full scale tests were performed. The superstructure and the dynamic vibration absorber were modelled into two degrees of freedom system with the help of FEM analyses. The experimental results were compared with the results calculated by the simple formula of two degrees of freedom systems. They generally showed good correlation. The vibration of the superstructure of a 40,000 DWT cargo ship was reduced to one fourth of the original vibration level by using a dynamic vibration absorber with a 800 kg weight. The dynamic vibration absorber has the following advantages: (1) Its installation requires only room for the device in the vibrating structure, making it economical. (2) The dynamic vibration absorber itself generates no vibration, or noise, because it requires no power source. (3) The effect of a dynamic vibration absorber on the vibration reduction is constant and reliable.

• 社団法人日本船舶海洋工学会の論文

著者

• Ohta Tohru

  Engineering Research Center Nkk Corporation

• Kondo Kiyoshi

  Electronic Research Center Nkk Corporation

• Satoh Hirokazu

  Planning And Administration Dept. Shipbuilding And Structure Division Nkk Corporation

関連論文

• 11. Vibration Control of Superstructure of Ships by Means of a Dynamic Vibration Absorber with Adjustable Natural Frequency

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