bravo zulu 1/2008 - GL Group

claSSIFIcaTIon
Second naval Submarine in class
The second naval submarine has
been submitted into GL class. The
conventional class 209 submarine
of type 1400 MOD for the South African
Navy was built by the German
Submarine Consortium, consisting
of Howaldtswerke Deutsche Werft AG
(HDW), Kiel, Nordseewerke GmbH
(NSWE), Emden, and MAN Ferrostaal
AG, Essen. Delivery took place in November
2006.
The submarine “SAS Charlotte
Maxeke” has received “100 N 6 Submarine”
classification, the machinery
plant was classed as “MC U” in June
2008. The sister vessel “SAS ‘Mathatisi”
was successfully classed last year
cUSTomER SERVIcE
network Expanded
In order to provide worldwide navies with
a single point of contact and enhance onsite
customer service, GL appointed Naval
Business Development Manager (BDM).
They will interact with GL’s local representatives,
all other internal and external
technical and administrative specialists
to carry out naval projects. Headquarters
will prepare proposals, run projects and
support field sales.
The traditional range of services includes
comprehensive classification
services for newbuildings based on GL
design requirements for surface craft and
submarines, safety consulting for ships in
operation, as well as a wide range of engineering
services such as assessment of the
strength of pressure hulls against buckling,
sufficient fatigue life capacity, resistance
against underwater explosions or vibration
behaviour.
“Much like in commercial shipping,
these surveys are an excellent means of
identifying wear and tear early on, thus
helping to avoid more costly repairs at a
later date,” said Lorenz Petersen, Head of
Navy Projects. For newbuilding projects,
GL’s global network of surveyors handles
the full spectrum of construction monitoring
services using modern software tools.
Following the approval of a newly-built naval
vessel, the ship continues to undergo
technical inspections at regular intervals
while in service.
Additionally, GL opened a new office in
Berlin. Dietmar Gossel, who is the on-site
Liaison Officer, acts as contact person for
authorities, institutions as well as governmental
agencies and navies in the federal
capital. ■
contact details: Dietmar Gossel, Liasion Officer,
Phone: +49 30 2092-4168,
E-Mail: dietmar.gossel@gl-group.com
as the first naval submarine worldwide.
The South African Navy had
commissioned GL with the classification
of a total of three submarines.
The order includes the inspection
of the construction plans as well as
annual technical safety checks. The
third vessel will be inspected at the
end of 2008. In classifying newly-constructed
submarines, Germanischer
Lloyd’s services include the inspection
of construction drawings, materials,
joining, propulsion and systems
technology, as well as supervision of
construction and testing. GL also
tests and certifies fuel cells and other
AIP systems. ■
acoUSTIcS
noise under control
Ships are known to radiate noise
in all frequency bands, with the
highest sound levels at the lowest frequencies.
Reducing the radiated noise
level as far as possible, be it on board
or outside the ship, is one of the GL
Acoustics department’s main tasks.
For naval vessels in particular, it is of
great advantage to reduce the level
of waterborne noise to make the ship
more difficult to detect.
For very high frequencies (structure-borne
noise), the standard FEA
approach to vibration analyses is impossible
due to excessive computational
requirements. For a typical passenger
vessel for a frequency of 1,000
Hz, a FEA vibration model would lead
to several million degrees of freedom.
VIRTUal.
gl noiseFEm grid applied on the
validation of radiated noise of a mine-hunter.
noISE and VIBRaTIon – gl’S SERVIcE
If you would like to be informed about
noise and vibration analyses, please contact
Jürgen Jokat, GL’s Head of Acoustics.
Cooperation should start as early as possible,
preferably in the conceptual design
stage. If desired, standardized parts of the
SUBmaRInE EXpERTS (from l. to r.). Burkhard lilienthal (automation),
Joachim Zipfel (Electrical Systems), dr lars grünitz (Senior
manager naval Services) and matthias Schmidt (Steam Boilers
and pressure Equipment).
However, the fact that information is required
only averaged over a frequency
band allows an alternative, far more efficient
approach based on statistical energy
analysis (SEA).
The Noise Finite Element Method
(GL NoiseFEM) of Germanischer Lloyd
is based on a related approach. GL
NoiseFEM predicts the propagation of
structure-borne noise energy by analysing
the exchange of energy between
weakly-coupled subsystems. Validation
with full-scale measurements shows
that the accuracy of GL NoiseFEM is sufficient
for typical structure-borne noise
predictions in the frequency range between
80 Hz and 4,000 Hz.
Structure-borne noise analyses have
been validated on the wetted shell and
meet the requirements, which is an
important step towards predicting the
radiated noise of vessels. GL NoiseFEM
structure-borne noise analyses have
been already applied since 1997 to
support the design of mega
yachts, navy and passenger
ships. ■
For further information:
Jürgen Jokat,
Head of Acoustics,
Phone:
+49 40 36149-9 8,
E-Mail: juergen.jokat@
gl-group.com
work scope can be conducted by the shipowner,
for example, establishing the finite
element model or local vibration analysis
with GL training and supervision. Noise
and vibration measurements such as SAT,
HAT, FAT are also offered.
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