Finite element investigation on the static response of a composite catamaran under slamming loads

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Ocean Engineering 31 (2004) 901–929 www.elsevier.com/locate/oceaneng Finite element investigation on the static response of a composite catamaran under slamming loads Roberto Ojeda a , B. Gangadhara Prusty b, , Marcos Salas a a Institute of Naval and Maritime Sciences, University Austral of Chile, Casilla 567, Valdivia, Chile b Department of Maritime Engineering, Australian Maritime College, P.O. Box: 986, Launceston, TAS 7250, Australia Received 7 April 2003; accepted 13 August 2003 Abstract This paper presents the structural response of a fast and relatively small, composite mate- rials catamaran to slamming loads. Finite element method is used to provide valuable infor- mation in order to optimise the design of the catamaran. The analysis is carried out using ANSYS 6.0 finite element software. The response of the structure to quasi-static slamming loads according to Det Norske Veritas High Speed and Light Craft crest landing and hollow landing rules [DNV, 1999] has been implemented and studied. An optimisation study for the structural response is carried out by changing the ply orientation in the vessel and suitable recommendations are made. # 2003 Elsevier Ltd. All rights reserved. Keywords: Finite element analysis; Fibre-reinforced composite; Ship’s structures; High-speed crafts; Slamming loads 1. Introduction The demand for high-speed sea transportation has increased dramatically in the last 15 years. Since high speed is very closely related to the weight of the vessel, to achieve these new speed requirements, designers began to use lightweight materials in place Corresponding author. Tel.: +61-3-6335-4741; fax: +61-3-6335-4720. E-mail address: [email protected] (B. Gangadhara Prusty). 0029-8018/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.oceaneng.2003.08.008

Transcript of Finite element investigation on the static response of a composite catamaran under slamming loads

� Corresponding author.

E-mail address: g.prusty

0029-8018/$ - see front ma

doi:10.1016/j.oceaneng.200

Tel.: +61-3-6335-4741; fax: +61-3-6335-4720.

@mte.amc.edu.au (B. Gangadhara Prusty).

tter # 2003 Elsevier Ltd. All rights reserved.

3.08.008

Ocean Engineering 31 (2004) 901–929

www.elsevier.com/locate/oceaneng

Finite element investigation on the staticresponse of a composite catamaran under

slamming loads

Roberto Ojeda a, B. Gangadhara Prusty b,�, Marcos Salas a

a Institute of Naval and Maritime Sciences, University Austral of Chile, Casilla 567, Valdivia, Chileb Department of Maritime Engineering, Australian Maritime College, P.O. Box: 986,

Launceston, TAS 7250, Australia

Received 7 April 2003; accepted 13 August 2003

Abstract

This paper presents the structural response of a fast and relatively small, composite mate-rials catamaran to slamming loads. Finite element method is used to provide valuable infor-mation in order to optimise the design of the catamaran. The analysis is carried out usingANSYS 6.0 finite element software.The response of the structure to quasi-static slamming loads according to Det Norske

Veritas High Speed and Light Craft crest landing and hollow landing rules [DNV, 1999] hasbeen implemented and studied. An optimisation study for the structural response is carriedout by changing the ply orientation in the vessel and suitable recommendations are made.# 2003 Elsevier Ltd. All rights reserved.

Keywords: Finite element analysis; Fibre-reinforced composite; Ship’s structures; High-speed crafts;

Slamming loads

1. Introduction

The demand for high-speed sea transportation has increased dramatically in the

last 15 years.Since high speed is very closely related to the weight of the vessel, to achieve

these new speed requirements, designers began to use lightweight materials in place

R. Ojeda et al. / Ocean Engineering 31 (2004) 901–929902

of steel. One of the most common materials used to achieve lightweight structuresin small to medium size high-speed vessels are composites.Higher speed also means additional loads to the vessel’s structure. One of the

most critical of this additional loads is slamming, which occurs when the vessel’smotion causes an impact between her bottom or bow flare plating (also cross deckstructure in multihulls), and the water surface.The behaviour of a composite vessel structure under these loads is studied apply-

ing the finite element method. Classification societies recommended design loadsand load cases were used to perform the analysis of the vessel’s structure.This paper reports on a finite element analysis of the behaviour of a small com-

posite vessel under such loads, according to DNV HSLC (1999) crest landing andhollow landing loadings.

2. Literature review

Case studies on the state-of-the-art computer simulation and modelling techni-ques, using I-DEAS Master Series mechanical aided engineering software, appliedon the design of INCAT’s large wave piercing aluminium catamarans was pre-sented by Yakimoff (1997). The author highlights the importance of the use ofsophisticated computer techniques to prove new concepts, improving safety and toquickly optimise structures of this kind of vessels.Morris (1991) carried out a three-dimensional finite element model structural

analysis, using NASTRAN finite element package, of the entire hull and super-structure of a large aluminium alloy wave-piercing catamaran. Quasi-dynamicanalysis was used to identify field and concentrated stresses within suitable globaland local structural models. Loading patterns were applied according to Lloyd’sRegister rules and deflections and stress distribution were studied.However, above works have been focused on large high-speed catamarans built

using isotropic materials such as aluminium alloys.Hughes (1997) presented a strategy for achieving first principles optimum structural

design of a ship, using MAESTRO finite element software. He demonstrates that strat-egy for a large monohull fast ferry, first using all aluminium and then adapting thedesign to be all composite. DNV HSLC (1999) rules were used to perform the analysis.The author highlighted the dramatic structural weight saving that can be

achieved by using composite materials (13% of the total displacement of a 100 mlength monohull fast ferry).He also remarks that there was not enough time available to do a true optimum

design for the composite ship model, which means that no change in scantlings orply orientations were implemented on the sandwich panels of the model.Pettersen and Wiklund (1999) have explained different levels of direct calcula-

tions, according to DNV HSLC (1999) rules, applicable for various sizes and typesof crafts. They have mentioned that the global strength of a high-speed craft withlength above 50 m shall be analysed using a global finite element model, extendingover the total hull length and have a mesh size which can represent the overall stiff-ness and global stress distribution in the primary hull structure.

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A designer’s guide to the methodology used in the development and application ofthe required design loads according to the DNV (1999) rules for classifying highspeed and light crafts have been presented by Olbjørn et al. (1991). The authors men-tioned that for the case of planning and semi-planning craft (V=

ffiffiffiffiL

pi3) two quasi-sta-

tic slamming load cases should be analysed: crest landing and hollow landing.Formulations for transverse bending moment, vertical shear force and also twin hullpitch connection moment (due to torsion loading) are also given for multihull vessels.Direct calculation methods for the global strength analysis of high-speed com-

posite crafts with length less than 50 m and a length to depth ratio less than 12have not been recommended by any authors or rules so far. However, Kastak(1998) carried out an FE global strength analysis of a small aluminium catamaran(7.9 m length) using DNV HSLC (1999) rules.The same approach is used in the analysis of the present vessel, which is only

17 m long.

3. Description of the vessel

The vessel used for this analysis was built in Chile by Alwoplast according to aCrowther Multihulls design. She is a 16.76 m long, high speed, composite materi-als, power-yacht catamaran. She is capable of achieving a maximum speed of 28knots. The general arrangement of the vessel is shown in Fig. 1.

Fig. 1. General arrangement of the composite catamaran.

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This vessel operates as a pleasure craft in the inland, inshore and coastal watersof the bays and channels of Chiloe, in the southern part of Chile (South America).The principal parameters of the vessel are presented in Table 1.The vessel was constructed using glass fibre-reinforced composites for the outer

and inner skins and closed cell foam as the sandwich core material. Table 2 pre-sents eight different lamination schemes for different parts of the vessel’s structureand the total thickness of each one, including the inner and outer skin and sand-wich core. All curved panel laminations were made by hand layout method infemale mould. Vacuum bag process was used in flat areas, such as bulkheads.

4. Finite element analysis using ANSYS 6.0

Two different element types (SHELL99 and MASS21) are utilised to create thefinite element model. The full structure of the composite vessel was representedusing SHELL99 layered shell elements (shown in Fig. 2). This element is an 8-node, 3-D shell, layered element with six degrees of freedom at each node: trans-lation in the nodal x, y and z directions and rotations about the nodal x, y and zaxes. It is designed to model thin to moderately thick plate and shell structureswith a side-to-thickness ratio of roughly 10 or greater. The SHELL99 elementallows a total of 250 uniform-thickness layers.

Table 2

Laminations schemes

Lamination

Thickness (m)

Lamination 1-hull bottom and sides

0.034

Lamination 2-underwing

0.044

Lamination 3-deck and superstructure sides

0.022

Lamination 4-superstructure roof

0.032

Lamination 5-no watertight bulkheads

0.021

Lamination 6-watertight bulkheads

0.023

Lamination 7-accommodation floor

0.022

Lamination 8-keel

0.105

Table 1

Principal parameters of the catamaran

Parameter

Dimension/details

Length overall

16.76 m (55 ft)

Length waterline

14.10 m

Beam overall

6.00 m

Beam waterline

5.88 m

Draft (cwl)

0.80 m

Displacement (cwl)

18.00 metric ton

Engines

2� 225 kW

Propulsion

Two water jets

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The performance of the element has been validated by running some benchmark

examples from the open literature (see Appendix A).The element SHELL99 was defined at seven different sections (Fig. 3) of the hull.

This method is useful to check the geometry and attributes during pre-processing

and to have a quick access to the results in the post-processing stage.MASS21, shown in Fig. 4, is selected as the element to define lumped masses in

the vessel, such as engines, fuel, fresh water, etc. This is a point element having six

degrees of freedom: translations in the nodal x, y, and z directions and rotations

about the nodal x, y, and z axes.

Fig. 2. SHELL99 element.

Fig. 3. FE model sections.

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The element is defined by a single node and concentrated mass components(Force� Time2=Length) in the element coordinate directions. Real constants areused in SHELL99 to define numbers of layers, layer orientation angle, layermaterial and layer thickness. Ten different real constants, shown in Table 3, aredefined to represent the eight different lamination schemes of the vessel structureplus the windows and the water jets.Real constants are used in MASS21 to define the lumped mass applied to each

element in x, y and z directions of the different items such as engines and compo-nents of the deadweight.All the seven different real constants are presented in Table 4.Material property directions for orthotropic materials are parallel to the layer

coordinate system, which is defined by the element coordinate system and the layerorientation angle (defined in the real constants). A list of all the materials used inthe finite element model is presented in Table 5.

Table 3

SHELL99 real constant table

SHELL99 real constant number

Item

1

Hull sides and bottom

2

Underwing

3

Deck and superstructure sides

4

Superstructure roof

5

No watertight bulkheads

6

Watertight bulkheads

7

Accommodation decks

8

Keel

9

Windows

10

Water jets

Fig. 4. MASS21 element.

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4.1. Mesh generation

The geometry of the model, shown in Fig. 5, is created by defining keypoints

from the table of offsets of the hull. Areas are then defined in terms of those key-

points and attributes (element type, element coordinate system orientation, real

constant) are assigned to the areas and keypoints based on the information pro-

vided by the designer. Then, a mesh is generated, using the automatic meshing

facility of the pre-processor module of ANSYS 6.0.The ANSYS 6.0, finite element model consists of 10 620 nodes with six degrees

of freedom per node and 4868 elements (4461 SHELL99 and 408 MASS21).

4.2. Boundary conditions

Global constraining of the loaded model was avoided by adoption of a free body

support, which was arranged to provide the necessary reference point for the

‘‘Inertia Relief’’ [3] facility of the ANSYS program.

4.3. DNV hollow landing and crest landing slamming load cases

Within the global loads recommended by DNV (1999), two static slamming load

cases, hollow landing (HL) and crest landing (CL), are specified. The load calcula-

Table 5

Material list table

Number

Material Type

1

Chop strand mat Isotropic

2

Unidirectional Orthotropic

3

Woven roving Orthotropic

4

Biaxial DB170 Orthotropic

5

Triaxial CDB 200 Orthotropic

6

Triaxial CDB 340 Orthotropic

7

Divinycell H80 Orthotropic

8

Coremat Isotropic

9

Glass Isotropic

10

Steel Isotropic

Table 4

MASS21 real constant table

MASS21 real

constant number

Item N

umber

of nodes

N

odal mass (kg)

11

Engine 8 2 12.5

12

Galley and dining room area 63 42.5

13

Toilets 40 31.2

14

Bridge 87 31.0

15

Daily fuel tank 28 33.0

16

Main fuel tank 1 50 24.0

17

Fresh water tank 32 31.3

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tions for both load cases are preformed according to the method presented by

Kastak (1998).For both cases, the hull girder is considered out of the water and the weight of

the structure is to be increased by the design vertical acceleration at longitudinal

centre of gravity (LCG).The design vertical acceleration may be calculated according to the rules.

acg ¼VffiffiffiffiL

p � 3:2

L0:76� fg � g0 m=s2 ð1Þ

where fg is an acceleration factor dependent on the type of service notation and

service area restriction. Yacht vessel type and coastal service area restriction deter-

mine a factor of 1.0; g0 is the acceleration of gravity, 9.81 m/s2; L is the length of

the craft in metres defined as the distance between perpendiculars, which for this

case is 14.10 m.V=

ffiffiffiffiL

pneed not to be taken greater than 3.0 for this case.

Thus, substituting these values into Eq. (1), the vertical design acceleration yields

12.6 m/s2.In hollow landing condition, it is assumed that the vessel is settled down on a

hollow wave, which is positioned along the length of the vessel. Thus, the vessel is

assumed to be supported on the hollow landing reference areas, placed at the bow

and stern of the ship (Fig. 6). The value of the reference area, based on DNV

Fig. 5. Catamaran FE model.

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HSLC (1999) rules for hollow landing, was found to be 16.05 m2. Each hull carriedhalf of this area, divided in a fore and aft area, with a surface 4.01 m2 each.A longitudinal midship bending moment for the hollow landing case, according

to DNV rules, is calculated as below.

Mb ¼D2ðg0 þ acgÞðer ewÞ kN m ð2Þ

where D is the displacement of the vessel in tonnes, 18 ton for the studied vessel; g0is the acceleration of gravity, 9.81 m/s2; acg is the design vertical acceleration, 12.6m/s2; er is the mean distance from the centre of the hollow landing reference areasto the vessel LCG in metres, 4.5 m; ew is half the distance from LCG of the forehalf body of the vessel to the LCG of the aft body of the vessel in metres, 2.95 m.On appropriate substitution of values in Eq. (2), the longitudinal midship bend-

ing moment was found to be 313 kN m.For this static and freely supported ship structure, the values of bending

moments calculated from either end (fore and aft half bodies) have to be equal toeach other and also similar to the moment value calculated using the DNV (1999)rules. Also the sum of the forces due to the slamming pressure acting on the hollowlanding reference areas must be equal to the weight of the structure increased by

Fig. 6. Hollow landing areas.

Fig. 7. Hollow landing loading condition.

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the design vertical acceleration. These equilibrium conditions, shown in Fig. 7, maybe written as a set of two linear equations as:

Fa þ Fb ¼ ðMaft þMforeÞðg0 þ acgÞ ð3Þ

Fadaft Maftðg0 þ acgÞlaft ¼ Fbdfore Mforeðg0 þ acgÞlfore ð4Þ

On solving the simultaneous equations the forces are calculated as

Fa ¼ 208 kN

Fb ¼ 194 kN

The force acting on each hull is obtained by dividing each force by 2. Thus, theslamming pressures, for the hollow landing case, were obtained by dividing theforces acting in each hull into the hollow landing reference areas.

Pa ¼ 25 kPa

Pb ¼ 26 kPa

So for the midship bending moment, the calculation is,

Fadaft Maftðg0 þ acgÞlaft ¼ 330 kN m

or

Fbdfore Mforeðg0 þ acgÞlfore ¼ 330 kN m ð5Þ

Hence, a close agreement has been obtained between the resulting bendingmoments for aft and fore bodies and the rule bending moment.The slamming pressure for hollow landing was applied, to the finite element

model, on the elements within the hollow landing reference areas as presented inFig. 8.In crest landing condition, it is assumed that the vessel is settled down on a wave

crest, which is positioned along the length of the vessel. Thus, the vessel is assumedto be supported over crest landing reference area placed with its centroid at theLCG of the vessel, as shown in Fig. 9. The value of the reference area, based inDNV HSLC (1999) rules, for crest landing was found to be 19.75 m2. Thus, eachhull carried half of this area, which was a surface of 9.87 m2.The longitudinal midship bending moment for the crest landing case is calcu-

lated as shown below

Mb ¼D2

g0 þ acg� �

ew ls4

� �kN m ð6Þ

where D, g0 and acg have been previously defined; ew is half the distance from LCGof the fore half body of the vessel to the LCG of the aft body of the vessel inmetres, 2.95 m; ls is longitudinal slamming reference area, 6.7 m.

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Thus, on substitution of values into Eq. (6), the longitudinal midship bendingmoment yield 255 kN m.Following the same procedure adopted for hollow landing case, equilibrium con-

dition (Fig. 10) for crest landing case is written as a linear equation as:

F ¼ ðMÞðg0 þ acgÞ ð7Þ

On solving Eq. (7) the force obtained is

F ¼ 400 kN

Fig. 9. Crest landing area.

Fig. 8. Hollow landing loads in the FE model.

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meaning that the force to be applied to each hull is

Fh ¼ 200 kN

Hence, the slamming pressure, for the crest landing case, is obtained by dividingthis force into the crest landing reference area of each hull.

P ¼ 20:3 kPa

The midship bending moment is calculated by splitting the hull weight and thecrest landing area into two parts at the midship section.

Fadaft Maftðg0 þ acgÞlaft � 140 kN m

or

Fbdfore Mforeðg0 þ acgÞlfore � 140 kN m ð8ÞThis bending moment is found to be almost 37% less than the one calculated

using the DNV (1999) crest landing rules. However, the difference can be attributedto the concentration of the ship weight (Fig. 11), over the crest landing referencearea.The slamming pressure for crest landing is applied, to the finite element model,

on the elements within the crest landing reference areas as presented in Fig. 12.

5. Analysis and discussion

The finite element model is analysed for each load case using ANSYS 6.0 sparsematrix solver in a Intel Pentium IV Proccessor. Deflection and stresses, for theDNV HSLC (1999) load cases are analysed. In order to check imbalances of themodel, the accelerations applied by the inertia relief facility were checked and arefound to be very small in magnitude, which confirm that only minor force imbal-ances were present on the model.

Fig. 10. Crest landing loading condition.

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Fig. 12. Crest landing loads in the FE model.

Fig. 11. Weight distribution plot.

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5.1. Hollow landing load case

The deformed plot of the model for the hollow landing load case is presented in

Fig. 13. Displacements have been increased by a factor of 20 to provide a clearer

indication of the deformed shape. The deflections at both ends of the vessel are

found to be non symmetrical, that attributed to the non uniform mass distribution

presented in Fig. 15. The maximum vertical deflection, of about 39 mm, is noted to

occur at the forward end of the vessel.Maximum axial (tension and compression) stresses were studied along each sec-

tion and lamination scheme of the vessel. High stress concentration points are

identified. Fig. 14 shows the distribution of the maximum axial stresses in x, y and

z axes for each section of the vessel in hollow landing condition. Maximum axial

stress in tension (76 MPa) and maximum axial stress in compresion (51 MPa) are

found to occur at the ring frame in the forward part of Section 1. The stress con-

centration points are shown in Figs. 15 and 16, respectively. Fig. 17 shows the dis-

tribution of the maximum axial stresses in x, y and z axes for each lamination of

the vessel in hollow landing condition.

Fig. 13. Vertical deflection of the hull girder in HL condition.

915R. Ojeda et al. / Ocean Engineering 31 (2004) 901–929

Fig. 14. Maximum axial stress by section plot for HL condition.

Fig. 15. Maximum stress concentration plots for HL condition (tension).

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Fig. 16. Maximum stress concentration plots for HL condition (compresion).

Fig. 17. Maximum axial stress by lamination plot for HL condition.

917R. Ojeda et al. / Ocean Engineering 31 (2004) 901–929

5.2. Crest landing case

The deformed plot of the model for the crest landing load case is presented in

Fig. 18. Displacements have been increased by a factor of 20 as in the hollow land-

ing case. The maximum vertical deflection, of about 22 mm, is observed to occur at

the forward end of the vessel.In this case also, the maximum axial (tension and compression) stresses are

plotted along each section and lamination scheme of the vessel. High stress con-

centration points are identifed. Fig. 19 shows the distribution of the maximum

axial stresses in x, y and z axes for each section of the vessel in crest landing con-

dition.The maximum axial stress in tension (55 MPa) is found to occur at the line of

union of the acomodation deck floor and the hull side in Section 5 (Fig. 20). The

maximum axial stress in compresion (37.5 MPa) is observed to occur at the acomo-

dation floor at the centreline in Section 3 (Fig. 21). Fig. 22 shows the distribution

of the maximum axial stresses in x, y and z axes for each lamination of the vessel

in hollow landing condition.

Fig. 18. Vertical deflection of the hull girder in CL condition.

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Fig. 20. Maximum stress concentration plots for CL condition (tension).

Fig. 19. Maximum axial stress by section plot for CL condition.

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Fig. 22. Maximum axial stress by lamination plot for CL condition.

Fig. 21. Maximum stress concentration plots for CL condition (compresion).

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Table 6

Change in ply orientation

Item O

riginal orientation (frames) Proposed orientation (frames)

Biaxial fibre DB170 4

5 0

Core –

Biaxial fibre DB170 4

5 0

Fig. 24. Maximum axial transverse stresses by lamination/crest landing.

Fig. 23. Maximum axial transverse stresses by lamination/hollow landing.

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5.3. Optimisation study

From both load cases, it can be seen that the maximum vaules of axial stressoccurs in the frames (transvese axial stresses (SX) in tension). The greatest occur-ing in the hollow landing case. In order to observe the global behaviour, a studyhas been performed by changing the ply orientation. The change in the ply orien-tation, shown in Table 6, was applied to the frames lamination scheme, in the finiteelement model. The model is then again solved for crest and hollow landing loadcases.The maximum transverse stress (SX) in the frames for the hollow landing and

crest landing cases is found to reduce by 34% and 21%, respectively, as shown inFigs. 23 and 24.Through out the remainder of the structure only minor changes, less than 5%,

were achieved, hence the plots are not presented.

6. Conclusions

A full, 3-D shell element, model of a small composite catamaran is created usingANSYS 6.0.The SHELL99 3-D shell element is satisfactorily tested and used to model lami-

nated composite structures. MASS21 nodal mass element is used for modellingconcentrated and distributed items of the ship weight.The applications of two quasi-static slamming load cases according to the DNV

HSLC (1999) rules, hollow landing and crest landing, were studied. Both loadcases were solved under a static linear approach using ANSYS 6.0.Deflection and stresses along the hull are studied to check the integrity of the

vessel structure. High stress concentration points were highlighted and changes inlamination schemes were trailed and maximum stress values were significantlyreduced.

Acknowledgements

The first author gratefully acknowledges the Australian Maritime College Coun-cil for awarding the Tom Fink Scholarship 2002 to carry out this investigation.The authors wish to thank Crowther Multihulls and Alwoplast S.A. for provid-

ing the information required to carry out this investigation.

Appendix A

A.1. Stiffened panel deflections

See Chattopadhyay et al. (1993), Tables 7 and 8, Figs. 25–28.

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Table 7

Geometry of the problem

Geometry of the panel

Length (m)

0.02540

Width (m)

0.02540

Geometry of the stiffener

Height (m)

0.00254

Thickness (m)

0.00025

Table 8

Lamination schemes of the problem

Name

Panel S tiffener

I-a

[0/0] [ 90/90]

II

[90/0/90] [ 90/0/90]

III

[0/90/0/90] [ 0/90/0/90]

Fig. 25. Description of the problem.

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Fig. 26. Results, lamination I-a.

Fig. 27. Results, lamination II.

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A.2. Shell deflections

See Wung (1997), Tables 9–13, Figs. 29–31.

Fig. 28. Results, lamination III.

Table 9

Material properties of the problem

Ex (N/m2) 1

:32Eþ 11

Ey (N/m2) 1

:08Eþ 10

Ez (N/m2) 1

:08Eþ 10

Gxy (N/m2) 5

:65Eþ 09

Gxz (N/m2) 5

:65Eþ 09

Gyz (N/m2) 3

:38Eþ 09

Prxy 0

.24

Prxz 0

.24

Pryz 0

.49

Thickness (m) 0

.000127

Table 10

Load

UDL ¼ 620:5 kN=m2

Table 11

Geometry of the problem

Geometry

r (m)

7.62

h (degrees)

40

l (m)

15.24

t (m)

0.0762

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Fig. 29. Description of the problem.

Table 12

Material properties of the problem

Material Properties

E1 (N/m2)

13:4Eþ 9

E2 (N/m2)

336:1Eþ 6

E3 (N/m2)

336:1Eþ 6

G12 (N/m2)

201:7Eþ 6

G13 (N/m2)

201:7Eþ 6

G23 (N/m2)

168:1Eþ 6

Pr12

0.25

Pr13

0.25

Pr23

0.25

Table 13

Lamination scheme of the problem

Lamination scheme

[0 0 0 45 45 90 90 90 45 45 0 0 0]

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Fig. 31. Vertical deflection.

Fig. 30. Lateral deflection.

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A.3. Plate moments

See Chen and Lui (1990), Tables 14–16, Figs. 32 and 33.

Fig. 32. Description of the problem.

Table 14

Geometry definition of the problem

Geometry Definition

a=b

1

a=h

10

Table 15

Geometry of the problem and load

Model Geometry

a (m)

0.127

b (m)

0.127

h (m)

0.0127

Load

qo (N/m2)

68:9Eþ 3

R. Ojeda et al. / Ocean Engineering 31 (2004) 901–929928

References

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Hughes, O., 1997. Two first principles structural designs of a fast ferry all-aluminum and all-composite.

FAST ’97.

Fig. 33. Moment results.

Table 16

Material properties of the problem

E1 (N/m2)

13:4Eþ 9

E2 (N/m2)

336:1Eþ 6

E3 (N/m2)

336:1Eþ 6

G12 (N/m2)

201:7Eþ 6

G13 (N/m2)

201:7Eþ 6

G23 (N/m2)

168:1Eþ 6

Pr12

0.25

Pr13

0.25

Pr23

0.25

929R. Ojeda et al. / Ocean Engineering 31 (2004) 901–929

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FAST ’97.