The hydro-elastic ship structural response might be an important part of the overall response. The difficulties related to the correct modeling of this type of structural response, either numerically or experimentally, are very important and it is fair to say that the problem is not fully mastered today. There are currently several research projects worldwide aiming at solving this problem, most of them combining numerical modeling, small scale model tests and full scale measurements. One of these projects is the WILS III project, in which model tests of an ultra large container ship flexible model are conducted in different operating conditions. The focus is made on the measurement of the bow flare impact loads that drive the whipping response, and on the improved modeling and measurement of the ship torsional behavior. To this purpose, a new elastic backbone has been fitted on the model, and an innovative procedure for torsion measurement has been proposed.
The first part of the paper is dedicated to the new measurement method. Torsion induced strains in the model backbone are influenced by the entire distribution of torsional moment, so that usual strain conversion procedures fail. The new method uses a base of distortion modes to take all strain gauges into account at once and overcome the difficulty.
In the second part of the paper, comparisons of a hydro-elastic numerical model with the model tests are presented. The numerical model is the combination of a full 3D FEM structural model and a 3D hydrodynamic model based on Boundary Integral Equation (BIE) technique. In addition, a 2D slamming model is added in time domain. Special accent is given to the oblique wave cases which are much more complex to model.
