Full scale wave and whipping induced hull girder loads
Author Aalberts P.J. and Nieuwenhuijs M.W.
Title Full scale wave and whipping induced hull girder loads
Conference/Journal Hydroelasticity in Marine Technology, Wuxi, China
Month Nov
Year 2006
Pages 14

Abstract
One year full scale measurements available from a general cargo/container vessel were analyzed to determine the effect of whipping on fatigue for a vessel with hull flare and bow flare as the Victoriaborg. The measurements utilized comprise the global strains in the midship region. From the global strains and ship’s geometric properties the hull girder bending moments were determined using a simple beam model. The wave and whipping induced hull girder bending moments and stress records were analyzed in detail.

In order to distinguish the wave frequent loads and the whipping loads, Fast Fourier Techniques were applied in order to obtain a high frequent part (whipping response), a low frequent part (wave frequent response) and the original response. Also various sailing speeds were considered up to 20 knots with a step size of 4 knots.

Information on the contribution of whipping to the wave induced vertical hull girder bending moment was obtained. Also the horizontal hull girder bending moment with respect to the vertical hull girder bending moments was determined.

The paper addresses the full scale monitoring campaign. Furthermore it describes the calculation methods applied to obtain from the measurements the fatigue damage originating from whipping with respect to the wave frequency loads.

Assuming also the low amplitude cycles contribute to fatigue, due to whipping the fatigue damage originating from the vertical hull girder bending moment increases with 30%.

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