Damping Factors in the Higher Modes of Ship Vibrations

An analysis is made of damping factors in the higher modes of ship vibrations. The solutions of the fundamental equation of the vibration of the uniform beam taking into account the effects of shear deflection, rotational inertia, internal damping force due to both of normal and tangential viscosities of a ship structure and the external damping force are obtained. The damping factors represented by logarithmic decrement in ship vibrations including higher modes are calculated from the solutions under the assumption of some numerical values of the damping coefficients. Some of the damping factors measured from the actual ships are compared with those obtained by the present theory. The empirical formula for estimating the damping factors in the higher modes of the hull vibration suggested by Dr. J. Lockwood Taylor is verified by the present theory.