Estimation of natural frequencies of torsional vibration of ships

Abstract

The characteristic values of the torsional vibration of a beam of variable cross section and with variable mass distributions like a ship’s form are computed from the solutions of the fundamental equation, and the formula for estimating the torsional vibration criticals of a ship’s hull by the use of the computed one is presented. The effects of the deck openings upon the torsional rigidity and of the virtual inertia of the entrained water mass in the case of torsional vibration on the natural frequencies are taken into account. The results of calculations are compared with measured ones in two types of cargo vessels.