OCTOPUS GRUPA – ISTRAŽIVAČKI RAD UZ PODRŠKU

OCTOPUS GRUPA – ISTRAŽIVAČKI RAD UZ PODRŠKU
PROJEKTANTIMA NA SLOŽENIM PROJEKTIMA
Zavod za brodogradnju i pomorsku tehniku,
Katedra za konstrukciju plovnih objekata
Department of Naval Architecture and Offshore
Engineering, Chair of Ship Structures
SUMMARY:
Application of the modern ship
structural design procedure is
presented on the mega yacht
example for all design phases
(concept, preliminary and detail).
Benefits of utilization of modern
rational design support technique
(FEM, optimization, etc.) are
demonstrated through achieved
results (reduction of weight/cost
and increase of safety). Approach
which employes full ship FEM
model which enables simulation
of the realistic 3D effects without
restricting assumptions proved to
be the right choice. Presented
work is a result of the successful
cooperation trough joint work of
industry and FSB research teams
and represents an example of
modern procedure in structural
design of complex ships.
OCTOPUS GROUP – RESEARCH SUPPORTING HIGH
LEVEL CONSULTING
MEGA YACHT (Loa = 100.8 m)
Based on the general arrangement plan developed
by VEGAYACHTS (VY) and the initial structural
design made by Rolls Royce Marine AS Merchant
Solutions (RRM), structural optimization and direct
calculation analysis of the mega yacht were
performed by FSB. Direct application of structural
support techniques during all phases of design
was performed with the following goals: reduction
of the structural weight, VCG position and
vibrations with simultaneous increase of overall
structural safety. Structural design was made on
the basis of Lloyd Register’s (LR) Rules for
passenger ships.
Industrial project with
VEGAYACHTS and Rolls Royce Marine
AS Merchant Solutions
2011 - 2012
Fig.5
Global hull girder free vibrations
(wet mode), f=2.73Hz - 1V.
Fig.1 General Arrangement - Profile (design by VY and RRM).
Concept design phase:
Objectives were to evaluate global strength and
contribution of the superstructure to structural
resistance to hull girder loads, cross sectional
stress distribution along the ship length, transverse
structure stress distribution due to racking and
force distributions in pillars.
Fig.6a
Substructures
free vibration
f=15.86Hz-1V
Main deck.
Fig.6b
Substructures
free vibration
f=15.02Hz-1V
Upper deck.
SAŽETAK :
Primjena moderne procedure
projektiranja konstrukcije broda
prikazana je na primjeru mega
jahte za sve faze projektiranja
(konceptualna, preliminarna i
detaljna). Prednosti primjene
modernog i racionalnog pristupa
podršci projektiranju (optimizacija,
MKE, itd.) demonstrirane su kroz
dobivene rezultate (smanjenje
mase i cijene te povećanje
sigurnosti). Prisup zasnovan na
primjeni MKE modela cijelog
broda koji omogućava simulaciju
realističnih 3D efekata bez
ograničavajućih predpostavki
pokazao se kao pravilan izbor.
Prikazani rad predstavlja rezultat
uspješne suradnje kroz združeni
rad industrijskog i FSB
istraživačkog tima te predstavlja
primjer moderne procedure
projektiranja konstrukcije složenih
brodova.
Preliminary design phase:
Main structural scantlings of the preferred mega
yacht model determined in concept design were
verified on more refined full ship FEM model.
Global hull girder and substructure free vibration
calculations (dry/wet) using full ship FEM model
were performed to verify acceptance of vibration
criteria, as a first step towards forced vibration
calculations. Comparision of results obtained by
eigenvalue solver developed by PMF (Grubišić
2011) and MAESTRO and NASTRAN solvers
was performed.
Fig.2 Vertical displacements for load case LC3 - Max. Hogging.
Two mega yacht full ship coarse mesh FEM models
of different length with the variable web frame
spacings in the superstructure and different framing
of the double bottom structure were optimized
regarding weight of steel structure using MAESTRO
and DeMak optimization framework extended trough
PhD Thesis (Prebeg 2011). Property based element
group approach was developed (Žanić, Pirić 2011)
and used in the optimization process. Efficient
optimal solutions were generated for the selection of
the preferred design variables. Optimal solutions
ranged in mass per length change 30.1 - 21.9 t/m,
where all respective safety values were increased.
Detail design phase:
Trough cooperation with SME Bonum d.o.o.,
FEM model from the preliminary design phase
was refined on fine mesh level to suit LR
requirements for verification of critical structural
details: large side screens, windows and other
large side openings, hull to arc structure
connection, critical details in the aft ship
structure, etc.
Fig.3 History of weight/safety changes through design cycles.
Full ship scantlings
Prototype SPL,D
Proposed Ship
Design SDL,D
Weight[t] / savings
VCG [mm]
Steel self weight
2129
0
6875
0
Light ship
4123
0
7360
0
Steel self weight
1878
-251
7647
772
Light ship
3872
-251
7782
422
Fig.4 Comparison of Prototype and corresponding Optimized Design.
Fig.7 Evaluation and redesign of critical structural details.
www.fsb.unizg.hr/octopus/ | V. Žanić, (Mentor/ Project leader) | Collaborators:
J. Andrić (Structural design of multi-deck ship); P. Prebeg (Optimization); M. Grgić
(Slamming loads); K. Pirić (Reliability based design); M. Stipčević (Design loads).