Springing Responses Analysis and Segmented Model Test on a 550,000 Dead Weight Tonnage Ore Carrier

Abstract

In hydroelastic model tests, segmented ship models are usually used to make sure that the model scale and the full size ship satisfy the similarity law of structural natural frequency and distribution of ship bending stiffness. However, springing barely occurs in those tests because the natural frequency of segmented ship models is too high for the regular waves required to be generated in a tank. In order to investigate the springing effect, three sets of backbone of variable cross section are adopted in the test. One set of backbones satisfies the similarity law of natural frequency, and two extra sets of low stiffness backbones are used so that the springing effect can appear and be measured. Experimental results show that the springing occurs when the wave encounter frequency coincides with the first elastic natural frequency of the ship, or with half or one-third of it. A good agreement has also been obtained between the experimental and the numerical results by a three-dimensional (3D) hydroelasticity method. Based on these results, the contribution of the springing responses to the fatigue damage of the ship is estimated and analyzed.