Navy Lighterage Replacement Program

Navy Lighterage Replacement ProgramNavy Lighterage Replacement Program

Lightweight Composite Lighter Module Prototype Development Program

Paul Coffin

NSWCCD Code 65539500 Macarthur Blvd

West Bethesda, MD 20817-5700301-227-5127

[email protected]

Deputy Program Manager: Dan McCluskeyNaval Facilities Engineering Command, (NAVFAC)

Project Manager: Himat GaralaCode 6551, NSWCCD

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• The Naval Facilities Command (NAVFAC) Sealift Support Program Office is evaluating alternatives to improve the current lighterage system by

– Reducing platform weight– Increasing load carrying capacity– Increasing throughput requirements

• One option for achieving these goals is use lightweight composite 40’ x 24’ x 8’ modules. This effort is investigating that option.

• This, and other prototypes, will be compared by at sea testing.

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Program Outline

• Program established to rapidly design and build a prototype– Establish loads– Concept development– Initial Design– Analysis– Prototype Contract– Fabricate Prototype– Test Prototype

• Activities– Naval Facilities Engineering Command (NAVFAC)………..Program Management– Naval Surface Warfare Center, Carderock Division (NSWCCD)……...Engineering– Northup Grumman Ship Systems..……………………………Prototype fabrication

All this to be completed in 18 months !

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Loads Definition

• Survive Sea State 5 (SS5)• High deck loads

– Vehicle loads• RCHT Vehicle

– Tire patch 31”x31” with 81 kips, equivalent to 84 psi

– RORO Ramp– Weight of Ramp and 2 vehicles ~

700 kips– Ramp load distributed by dunnage– Load assumed to be reacted by one

module• Load only 11 psi

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Hydrodynamic Loads

• Sea State 5 Loads– Modeled using WAMIT code (Wave Analysis, MIT).– Loads depend on

• module assembly geometry• position of hinged joints• Wave height, frequency and direction

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Design

24’

40’

8’

• Ballasting requirements and damage stability necessitated internal bulkheads

• Many concepts considered, but schedule drove a conservative design

• Rough scantlings calculated based on first principals

• End connection attachment major challenge

ConceptsConcepts

Final DesignFinal Design

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Fabrication Concept

• If concept selected, possible purchase of large numbers of modules.– Fabrication process must be adaptable to large scale production.

• Prismatic shapes (pultrudable, continuous lamination,…)• Self aligning parts

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Analysis

• Models built in FEMAP and analyzed in NASTRAN.• Global modeling of seaway loads on worst case assemblies

– Longitudinal Vertical Bending– Lateral Bending– Torsional Bending– Wave Slap: 1500 psf – Vertical Bending w/ RTCH Loading– Buckling Analysis

• Global results generated boundary conditions for detailed analysis of joints.

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Analysis

• Longitudinal Vertical Bending with RTCH loads

Top deck y stresses x stressesHull bottom 1st buckling mode

Max stress 24 ksiFS Buckling 2.1

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Analysis

• Lateral Bending

Max stress 7 ksi

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Analysis

• Torsional Bending

• Wave Slap

Max stress 14 ksi

Max stress 5 ksi

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Detailed/Joint Analysis

• Loads from global analysis fed into subsection detailed analysis.

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Material Testing

• Rapid schedule required material testing to occur after most analysis and during the prototype fabrication

• Northrup Grumman fabricated 24 oz. woven roving/VE panels for evaluation– VARTM– Vacuum bagged hand layup– Hand layup

• Material tests (ASTM standard tests)– Volume fractions– Tension– Compression– Inplane shear (“V” notched specimen)– Short Beam Shear (Apparent Interlaminar Shear Strength)– Bolt Bearing

• Tests validated material property assumptions used in the design and analysis.• Specimens are being conditioned at 120F, 80% Rh, for follow on tests.

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Outfitting/Deck Jewelry

• Module decks are populated with a diverse array of fittings

– Tie downs– De-watering holes– Hatches– Lifting eyes– Post Bitts

• Deck Jewelry placement used to assist structural attachment

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Alignment Feature

• Modules must be joined together in up to Sea State 3 conditions.

• Relative motion of ends can make joining difficult.

• Alignment feature designed to bring ends in phase to assist joining.

• Feasibility demonstrated in wave tank testing at the US Naval Academy.

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Prototype Fabrication

Fabricated by Northup Grumman Ship Systems, Gulfport, MS.

Materials: 24 oz/yd2 E-glass woven roving/Vinylester Resin, 9 and 15 lb/ft3 balsa core.

Process: Combination VARTM and hand layup.

Fabricated by Northup Grumman Ship Systems, Gulfport, MS.

Materials: 24 oz/yd2 E-glass woven roving/Vinylester Resin, 9 and 15 lb/ft3 balsa core.

Process: Combination VARTM and hand layup.

Contract Awarded October 2001Picture taken January 2002

Contract Awarded October 2001Picture taken January 2002

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Prototype Connector Testing

Load Arm

Transition

End Connector

Section

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Contact Information

• Please direct any questions relating to the US Navy’s Lighter systems to:

Mr. Dan McCluskey

Sealift Support Program OfficeNaval Facilities Engineering Command, (NAVFAC)

Washington Navy Yard, Washington, D.C.202-685-6012

[email protected]

Navy Lighterage Replacement Program

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