A Study on Evaluating Hull Girder Vibration in Initial Design Process

(Part 1, Simplified Evaluation of Natural Frequency for Double Bottom Structures)

Abstract

In case of study on hull girder vibration for the vessels having double bottom structures, it is well known a coupling effect of out-of-plane vibration on double bottom structures must be taken into account. In this paper, simplified evaluating method of the natural frequency for double bottom structures in initial design process is investigated. In previous paper, the authors have already proposed the simplified strength evaluation for the double bottom structures in consideration of shear deformation effects. The present paper is provided to estimate the fundamental natural frequency for double bottom structures with the various constraint conditions given by torsion beams on these boundaries. Through these studies, it is obtained that the proposed method is in practical use for the estimation of natural frequeney of double bottom structures because of good agreements with the results of finite element analysis.