18-12-2012, 06:06 PM
Ship-Shape Simulation
Ship-Shape Simulation.pdf (Size: 961.46 KB / Downloads: 34)
Designing ships is a demanding process, as vessels are among the most massive and mechanically
complex moving structures in the world. Ships must operate reliably in
harsh environments and meet stringent standards. Engineering demands are particularly challenging in designing work vessels for harbor and open-water applications, such as
hoisting, dredging, construction, pipe-
laying and other marine operations. The hull and internal structural members must be seaworthy and stable. In addition, topside mechanical assemblies, such as cranes, must provide sufficient strength and reliability
to work efficiently even while waves
excite the ship.
In separate analyses, ANSYS AQWA was used to study the motions
and loads of the lifting structure as waves of various heights and frequencies impact the vessel at different angles. In these studies, the vessel and crane structure were modeled separately from the lifted structure and then combined with representations of the connecting cables into a multibody hydro-
dynamic model. The engineering team determined the working range of the structure with respect to the sheerleg capacity and positioning accuracy.
Upgrading Lifting Capacity
In one recent project, VER engineers used the ANSYS tools to upgrade the lifting capacity of the Matador 3 sheerleg — a self-propelled floating crane used for lifting heavy
loads at the Rotterdam seaport docks
as well as for offshore construction projects, open-water wreck removal operations, and bridge and lock construction along inland rivers
and canals.
The Matador unit consists of two hinged, adjustable A-frame structures
with a hoisting jib held in place by a network of cables looped through
deck sheaves and controlled by main
power winches on the base of a pontoon platform.
Upfront Simulation
In another study, engineers used ANSYS Mechanical and ANSYS AQWA software in a one-way coupled simulation in which hydrodynamic pressure loads against the outside of the vessel hull calculated by ANSYS AQWA software were transferred directly into ANSYS Mechanical to determine the structural behavior of a trailing suction hopper dredging vessel. In particular, the study was
intended to check longitudinal bending of the critical midship region of the hull, calculate overall hull girder effects at the aft and fore hopper ends, and provide a detailed stress analysis
for evaluating girder fatigue.