Naval tools

The example used to describe a naval structure analysis will be a simple “Wigley” hull. It is standard model for validation of both experimental and numerical data. In order to make the calculation easier, symmetries will be considered.

Note that this example cannot be run with the free-limited version of RamSeries.

For basic reference, this example can be found in the distribution, directory Examples/RamSeries and with the name manual-stiffShellwave-ex7.gid .

A Wigley hull is created according to Equation 1, where parameters L , D and B represent length, beam and draft respectively.

y=B*0.5*(1-(2*x/L)2 )*(1-(z/D)2 ) Equation 1

For the example to be solved:

To create the hull, we are first going to create the NURBS lines defining the different waterlines of the model. The hull itself will be constructed as a NURBS surface based on those lines created in the previous step. In the following paragraph we will show the necessary steps to create the hull using the system preprocessor.

The surfaces defining the hull will be created using a batch file. This file is just a text file (ASCII format) containing the data points and a list of instructions. This instructions can be also inserted in the command line of the preprocessor module. Once the batch file has been created (and saved in a text ASCII file), it can be read using the option Read Batch file in the menu Files (or pressing Ctrl+B). By doing this, the next actions are carried out:

The result of this process (half of the ship geometry, due to the symmetry of the problem) is shown in the figure: