Joint High Speed Sealift (JHSS) Segmented Model Test Results

The Joint High Speed Sealift segmented model (Model 5663) tests performed in 2007, in the Maneuvering and Seakeeping Basin at the Naval Surface Warfare Center, Carderock Division, were designed to provide a large data set for validation of numerical simulations. Model 5663 is a segmented structural ship model that has scaled longitudinal bending and torsional stiffness. The scaled stiffness is obtained by building a backspline into the model that accounts for the bending stiffness and cutting the shell in several places, segmenting it to isolate the stiffness to the backspline. The alternative way to obtain structural loads would be to build a model with scaled plates and stiffeners; however, this would be very difficult and expensive. The backspline allows the stiffness to be scaled properly while using reasonable materials and simple construction. The hull segments of the model are connected with silicone to maintain a watertight connection. The model is self propelled and steered during data collection. The test matrix spans a wide set of wave conditions, including regular and irregular seas, with heading angles spanning the possible range. A wide range of speeds are also included, with Froude numbers ranging from 0 to 0.43. This test matrix, which includes about 2000 runs, allows for validation of codes from still water test, through operational conditions, to extreme design load determination. Different aspects of the data have been studied, but much is still left to be considered. An aspect of the model tests that has not previously been considered in detail is the hydroelastic response of the vessel. Hydroelastic phenomena are a subset of fluid-structure interaction problems where the elasticity of the structure is important. The vibrational characteristics of the model are determined. The main phenomena of interest are springing and whipping, and an analysis of the springing response and the whipping response in head seas is also discussed.