Experimental Investigation of the Influence of Bow Flare and Forward Speed on theNon Linear Vertical Motions, Bending Moments and Shear Forces in Extreme Regular Wave Conditions

摘要

An overview is given of all the results obtained from a series of towing tankexperiments in extreme regular wave conditions using two variants of a Wigley model. The difference between the models is the configuration of the bow geometry. The measured quantities have been the vertical motions, the longitudinal force and the vertical bending moment and shear force in the midship and a quarter of the length aft from the bow. Significant second and third harmonic contributions have been measured, especially in the hull girder loads. After normalization by the wave amplitude, the square of the amplitude and the cube of it respectively, amplitude-dependencies of the first, second and third harmonic frequency response functions are still observed. This is due to nonlinear contributions, higher than third order, which mix with lower harmonic responses. A direct relation between the degree of nonlinearity in the hull girder load responses and the relative motion at the bow exists. The peak frequencies of the relative motion frequency response function and the higher harmonic response functions coincide for all of them.