Digitising the drink

In a project for the US Navy, engineers are using a `virtual ocean’ to test the design of the largest floating structure ever envisioned: a self-propelled base bigger than ten aircraft carriers.

The proposed mobile offshore base (MOB) – which will provide the US with a sea-going alternative to bases on foreign soil – will be over a mile long, 500ft wide and 250ft high. As well as having a long enough runway to land fully loaded cargo planes, this leviathan will also have 85 acres of storage space and accommodation for 20,000 troops.

Obviously, it would be idiotic to begin a project of this size without first validating every aspect of the design, and this is where Mechanical Dynamics’ ADAMS mechanical simulation software comes in.

Engineers at the Gulf Coast Marine Technology Centre are using the software to determine how the MOB will operate in different conditions. Given the craft’s primary mission of logistical supply, how well it’s cargo systems bear up is of great interest, especially during rough seas that could affect the transfer of cargo to and from supply ships.

Using ADAMS software the engineers verified that this operation could be carried out in sea state four (wave heights of six ft).

CAD data defining the geometry of the MOB was used to create response amplitude operators in all six degrees of freedom. These motions and geometries were then brought together in ADAMS which analysed every load and force on each component and subsystem.

According to John Cardner, MOB project manager, the key to the success of this simulation will be the way in which his engineers have managed to integrate ADAMS with WAMIT – a wave body interaction program, and Coryphaeus’ Easy Scene visualisation package.