AlGOR Software give South American Shipbuilder the Edge
Learn how a Peruvian ship designing company benefited by updating their software operations through ALGOR.
Servicios Industriales de la Marina (SIMA)
(Peru, South America) is a state-owned corporate shipyard servicing the
Peruvian navy.
Recently, the company was contracted to build a steel barge that could
carry a 180-ton excavator and other equipment for digging a sub-sea
piping canal in Pisco Bay.
SIMA used FEA software (ALGOR, Inc., Pittsburgh, PA) to verify the
barge and meet the challenging design and fabrication schedule. With
the FEA, they designed a safe barge requiring less steel than had been
originally quoted and approved by the customer.
"We were able to deliver a fabrication drawing of the barge's spud legs
to our shop in less than a month," said Ed Cordova, SIMA structural
pro-jects chief designer. "All fabrication drawings were delivered in
less than two months and the barge was delivered to the customer within
four months."SIMA Enlists ALGOR'S Help
SIMA has three shipyards and a labor force of 1,200 for shipbuilding,
repairs, steelwork, electronic systems, and safety and defense. The
company had been modeling its designs with Mechanical Desktop and
Auto-CAD (AutoDesk, San Rafael, CA) but without the benefit of FEA.
They decided to get FEA software because it would allow them to quote
and design new projects faster while optimizing their existing designs.
SIMA would also be able to design steel structures of less weight
compared to previous manual designs. SIMA said it chose ALGOR because
its meshing and analysis capabilities were better suited to SIMA's
range of applications. Due to the tight schedule of the barge project,
the FEA system also had to be easy to learn. With the FEMPRO (ALGOR)
user interface, the application was easy to learn, Cordova said.
The primary engineering challenge in designing the barge was to ensure
that it would withstand the big-load operating conditions expected in
its round-the-clock service. The service loads of the excavator as well
as ocean wave surge, wind, and weights, including ballast and deck
equipment, had to be considered.
In addition to the excavator's 180-ton weight, its service loads were
calculated at 30 and 66 tons depending on the sea height. The ballast
was 210 tons and the deck equipment was 60 tons. The effects of maximum
wind speed of 28 knots and maximum wave height of 0.7 meters were also
considered. Cordova designed the spud legs, spud houses, and high load
zones of the barge. SIMA's engineering department chief designed the
general structure of the barge. Mechanical and structural CAD draftsman
used AutoCAD software to create shop drawings of the barge and spud
legs.
SIMA created finite element models of the general ship structure as
well as several components in high load zones, including the spud
helmet, bulkheads, and spud legs structure. Linear static and critical
buckling load analyses were performed to determine how the design would
withstand the expected loading conditions. The ALGOR analysis cut the
design cost by making the barge in less time. Ensuring safety and
reducing the steel quantity required by optimizing the design. The
model of the barge's structure consisted of four parts, the main
platform (modeled with 8 mm thick plate elements), supports (modeled
with truss elements), spud legs (modeled with beam elements), and spud
helmets (modeled with truss elements and used to apply loads to the
spud legs).
Static stress analyses with linear material models were performed for
several different load combinations and con-straints, which varied the
number of spuds pinned, the excavator position, the wave position, the
sea height, and the wind direction. They found through the simulations
that they could reduce the spud plate thickness from 19 to 12.5 mm for
9 meters of the spud length while maintaining structural integrity.
This reduced the amount of steel required to manufacture the spud legs.
"The models of the spud legs, spud boxes, spud houses, and high load
zones below the excavator were used for fabrication drawings," said
Cordova, "Using the FEA allowed us to design the high load zones very
fast and analyze various load combinations, which gave us better
understanding of the structures real behavior. This helped improve the
design by getting structures that weighed less, such as spud legs.
Designing and fabricating the barge would have taken much more time and
material."
For more information please contact Ed Cordova, structural projects engineer
with SIMA (Peru, South America), or Bob Williams, ALGOR, at (412) 967-2700.
