Instructions For Authors And Sample Paperdoc

=== Instructions for authors and sample paper ===

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instructions for authors and a sample paper

(14 pt bold with capital letters, two lines max.)

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First Name Surname1, First Name Surname 1, First Name Surname 2 (12 pt bold)

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1“Gheorghe Asachi” Technical University of Iasi-Romania, Department of Machine Manufacturing Technology (10pt)

Full address including zip code (10 pt)

2 Technical University “Dunarea de Jos” of Galati, Department of Machine Manufacturing Technology (10 pt)

Full address including zip code (10 pt)

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Corresponding author (who upload the abstract): First Name Surname, E-mail address (10 pt)

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Abstract: Abstract: The purpose of this paper is to calculate and assess the overall structural response of the oil/chemical tanker 37000 tdw, and to suggest structural improvements where necessary.

The hull structure considered in the 3-D global FEM model is limited to three cargo tanks in the parallel mid body.

The structural model was initiated using POSEIDON, then it was developed, solved and post processed using MSC NASTRAN for Windows.

The approach of finite element modeling adopted by GL Rules and Poseidon is to use a 3-D hold model to obtain the overall response of the hull girder under the imposed loadings.

The results from the global model analysis were used to assess the hull girder plating of the deck, side and double side shell, bottom, inner bottom, longitudinal and transverse bulkheads and the primary framing structure (longitudinal and transversal) .

Key words: POSEIDON, FEM Analysis, loading the structure , stress, stress concentrators, bending moment, maximum sagging bending moment.

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1. Introduction

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The main concern regarding the development with finite element is to generate a model providing the best possible results of the structural strength.

Sizing of the model was made in accordance with the rules of the classification company Germanischer Lloyd.

For modelling and analysis of the stresses around the relief cut-outs of a frame element, in this case of a floor, we used finite element software system FEMAP version 9.3.1.

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1.1 Main dimensions and characteristics

Length between perpendiculars Lpp = 172.00 m

Length of water line at T Lwl = 175.00 m

Rule length L = 169.75 m

Breadth B = 32.20 m

Depth H = 16.50 m

Scantling draught T = 11.00 m

Block coefficient Cb = 0.8

Max. speed in calm water v = 14 kn

Frame spacing in cargo holds area a = 0.8 m

Web frame spacing 4a = 3.2 m

Displacement 37000 dwt

Materials

Steel with:

E = 206900 N/mm² – Young’s modulus ;

G = 79577 N/mm² – Shear modulus;

ν = 0.3 – Poisson’s coefficient

1.2 Modeling the Structure:

The hull structure considered in the 3-D hold model includes three cargo tanks of the parallel mid-body, as shown in Figure 1.

The global coordinate system of the finite element model is defined as follows:

X-axis: Longitudinal, positive from aft to fore;

Y-axis: Transverse (athwart ships), positive toward portside;

Z-axis: Vertical, positive upwards;

Origin: Base-line.

The following units are used for analysis:
– Length: millimeters (mm);

– Pressure: Megapascals (N/mm2);

-Mass:kilogramme(kg);

– Stress: N/mm2 (MPa).

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2. THE 3D HOLD MODEL FEM ANALYSIS

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The approach of finite element modeling adopted by GL Rules and Poseidon is to use a 3-D hold model to obtain the overall response of the hull girder under the imposed loadings.

The results from the global model analysis were used to assess the hull girder plating of the deck, side and double side shell, bottom, inner bottom, longitudinal and transverse bulkheads and the primary framing structure (longitudinal and transversal) .

The following types of elements are used in the structural model :

Plate elements for the shell and main supporting members. The most of the plate elements are quadrilateral. Some triangular elements were used, where necessary. The thickness of the plate elements is shown in Error: Reference source not found.

Beam elements, with offset according to neutral axis position, for modelling the secondary framing (longitudinals, simple transverse framing, stiffeners on the webs, face plates of the primary structure) (see Error: Reference source not found).

Two rigid elements placed at the ends of the model, used to simplifiy the application of the boundary loads (forces and moments).

The adopted mesh size is of about 400mm in the center hold of the model used in the strength assessment (half of frame spacing), and of about 650mm in the lateral holds.

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3. LOADING THE STRUCTURE

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The loading cases include:

external pressures (still water and wave);

intrernal pressures (hydrostatic, dynamic effect, safety pressure valve, sloshing, heeling) self gravity of the model;

specific balanced boundary loads.

Cargo and ballast hydrostatic and hydrodynamic pressures corresponding to the following densities :

ρ = 1.025 t/m3 – massic density of the ballast water;

ρ = 1.025 t/m3 – massic density of the cargo in cargo tanks ;

Pressure from the safety valve in cargo tanks: pv = 0.2 daN/cm2

The acceleration factor used for multiplying the pressures values in the tanks (cargo and ballast) is 1.118 according GL Rules I-1-1, Sec.4, C 1.1

The horizontal wave forces and moments were neglected.

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3.1 L.C.1 – Alternate loading of cargo in holds – bending

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Ship on wave crest, maximum hogging bending moment (wave + static) obtained at middle of the structure (Fr.126).

The loading conditions for this loading case are :

external hydrostatic presures corresponding to Tmax (imported from Poseidon);

external pressures due to wave crest (imported from Poseidon);

internal pressures in the holds according to: GL Rules I-1-1, Sec.4, D1 (see Error: Reference source not found);

boundary forces and moments were aplied at both ends of the structure in order to obtain the maximum bending moment (hogging – wave + static) at the middle of the structure (Fr.126). According to GL Rules I-1-1, Sec.5, C,5 the maximum bending moment is:

MT = Msw + 75%Mwv =1.1361E+12 + 9.7984E+11 = 2.11594E+12 [Nmm]

where Msw is the maximum still water bending moment from all the existing loading cases.

the boundary loads were applied so that the model remains in equilibrium:

as recomended by GL, 3 nodes placed at the ends of the model, near the neutral axis, were fixed in order to exclude rigid body motions. The reaction forces resulting in these nodes are negligible.

ccesed: 23/11/2010.