Experimental investigation on a flapping beam with smart material actuation for underwater application

Abstract

This paper presents an experimental investigation of flapping beam for thrust generation. The beam is studied in current of water and actuated by the “Macro-Fiber Composite (MFC)” based smart material to undergo flapping and undulatory motions, mimicking a fish. The results obtained are expected to be useful in designing process of robotic fish in different marine environment. Herein, the average power spent for actuation is measured and it is observed that the maximum efficiency obtained is 55% for the frequency of 2.0 Hz. The set of experiment of the undulatory smart beam conducted at different depths of submergence showed that an increase in depth of submergence lead to increase of the thrust. However, in the region between the free surface and bottom of the channel (i.e. mid-depth) the thrust is low. By analyzing the measured data, threshold value of “Elastio-Inertia” number for low input power and high efficiency is determined. The results obtained are expected to help in better understanding the swimming pattern, locomotion of fish and other sea creatures. Also, it contributes to the design and development of motor-less and gearless thrust generation mechanisms for the marine vehicles and robots.