Navy Lighterage Replacement Program Navy Lighterage Replacement Program Lightweight Composite Lighter Module Prototype Development Program Paul Coffin NSWCCD Code 6553 9500 Macarthur Blvd West Bethesda, MD 20817-5700 301-227-5127 [email protected]Deputy Program Manager: Dan McCluskey Naval Facilities Engineering Command, (NAVFAC) Project Manager: Himat Garala Code 6551, NSWCCD
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Navy Lighterage Replacement ProgramNavy Lighterage Replacement Program
Lightweight Composite Lighter Module Prototype Development Program
• 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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Navy Lighterage Replacement ProgramNavy Lighterage Replacement Program
Program Outline
• Program established to rapidly design and build a prototype– Establish loads– Concept development– Initial Design– Analysis– Prototype Contract– Fabricate Prototype– Test Prototype
• Global results generated boundary conditions for detailed analysis of joints.
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Navy Lighterage Replacement ProgramNavy Lighterage Replacement Program
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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Navy Lighterage Replacement ProgramNavy Lighterage Replacement Program
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.