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

2


• 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.

3


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 !

4


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

5


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

6


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

7


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

8


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.

9


Analysis

• Longitudinal Vertical Bending with RTCH loads

Top deck y stresses x stressesHull bottom 1st buckling mode

Max stress 24 ksiFS Buckling 2.1

10


Analysis

• Lateral Bending

Max stress 7 ksi

11


Analysis

• Torsional Bending

• Wave Slap

Max stress 14 ksi

Max stress 5 ksi

12


Detailed/Joint Analysis

• Loads from global analysis fed into subsection detailed analysis.

13


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.

14


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

15


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.

16


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

17


Prototype Connector Testing

Load Arm

Transition

End Connector

Section

18


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]

Documents

Navy Lighterage Replacement Program