lightweight modular causeway section (lmcs) research & development for tsv applications

LIGHTWEIGHT MODULAR CAUSEWAY SECTION (LMCS) RESEARCH & DEVELOPMENT FOR TSV APPLICATIONS

LIGHTWEIGHT MODULAR CAUSEWAY SECTION (LMCS)

TOPICS

• Buoyancy and Stability Characteristics of the LMCS Concept.– 1/12th Scale Model Buoyancy & Stability Tests– Failure Mode Evaluation

• Flotation Geometry Study• Inflated Structure

– Damage Containment & Mitigation– Air Containment Concepts


Buoyancy and Stability Characteristics of the LMCS Concept

A payload of a simulated Abrams tank (74 short tons) is positioned amidships to ascertain floatation

characteristics.


QED, Inc.Calibrated Test Facility

(1 Acre Pond)

QED, Inc.Calibrated Cat (Weight 25 lbs)

Buoyancy and Stability Characteristics of the LMCS Concept


1/12-Scale LMCS Buoyancy & Stability Tests

• The purpose of the tests was to evaluate the load-carrying capacity of the LMCS concept.

• The model was set in a special-purpose, water-filled tank with means of measuring attitude of each float and applied loads.

• All data was recorded on Excel spreadsheet.• Photographs were taken of key test features.



1/12th ScaleModel

Purpose Built Tank

CalibrationMethod For

Deck Position

Place HoldersFor Positioning

Weights



Pressure in bladders carefully controlled

LMSC modules heaveposition measured at

fixed points


• Model float identifiers• Model weight locations• Corner locations for

height measurements

The vertical locationof all four corners ofall six floats were readfor each test run

Float A

Float B

Float C

Float D

Float E

Float F

PF MF SF

PA MA SA

PF MF SF

PA MA SA

PF MF SF

PA MA SA




Weights were added in precise locations and recorded along with

platform position and bladder pressure

Roll characteristics were evaluated by off-

setting weights


• Runs 1-7 Pressure set to 0.2 psi (5.5 inches on water-filled manometer)

• Runs 8-22 Pressure set to 0.6 psi (15.5 inches on water-filled manometer)

• Runs 23-36 Pressure set to 0.6 psi (31 inches on water-filled manometer)

• Runs 37-45 Forward tube under Float Dvented to represent failure mode

• Runs 1-4 Adding weights to Float D only• Runs 5-6 Moving rows of weights forward



Runs 1-4. Heave stiffness is very linear

Heave Stiffness - 0.2 psi

E = 0.5119x + 1.0149

D = 1.0932x + 0.5569

F = 0.0038x + 1.6406

C = 0.5111x + 1.151

A = -0.0284x + 1.5828

B = 0.0398x + 1.5283

0.000

1.000

2.000

3.000

4.000

5.000

6.000

1 2 3 4

15 lb Load Increment

Heave Reading, inches

Float A

Float B

Float C

Float D

Float E

Float F

Linear (Float E)

Linear (Float D)

Linear (Float F)

Linear (Float C)

Linear (Float A)

Linear (Float B)



Runs 8-11. Heave stiffness increases with pressure


D = 0.8076x + 0.7535

E = 0.5119x + 1.0149C = 0.4709x + 1.1116

B = 0.1169x + 1.3658F = 0.0038x + 1.6406A = -0.0221x + 1.5203

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

4.500

1 2 3 4



Float A

Float B

Float C

Float D

Float E

Float F

Linear (Float D)

Linear (Float E)

Linear (Float C)

Linear (Float B)

Linear (Float F)

Linear (Float A)



Runs 23-26. Heave stiffness increases with pressure


D = 0.6923x + 0.75

C = 0.4859x + 0.9533

E = 0.463x + 0.8569

F = 0.2184x + 1.2123B = 0.2093x + 1.1034

A = 0.0301x + 1.3015

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

1 2 3 4



Float A

Float B

Float C

Float D

Float E

Float F

Linear (Float D)

Linear (Float C)

Linear (Float E)

Linear (Float F)

Linear (Float B)

Linear (Float A)




Load is supported by more floats as pressure is increased

Effect of Pressure on Float Heave

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

A B C D E F

Float

Percentage of Total Heave

Displacement

0.2 psi

0.6 psi

1.2 psi



Increasing pressure makes causeway stiffer

Effect of Pressure on Heave Deflection

y = 0.028x -3.319

0

2

4

6

8

10

12

0% 10% 20% 30% 40% 50% 60%

Percentage of Total Load Carried by Loaded Float

Pressure, psi

From stiffness analysis above

Trend of stiffness by analysis


Effect of Pressure on Float Heave

-10%

0%

10%

20%

30%

40%

50%

60%

A B C D E F

Float

Percentage of Total Heave

Displacement

0.2 psi

0.6 psi

1.2 psi

Load Spread

Failure Mode


Demonstration of failure mode and effect of load spread


Flotation Geometry Study

5.5-ft

10-ft

5-ft Dia

25-ft

1-ft Hard Structure Height

Baseline LMCS Concept Dimensions


Flotation Geometry Study

5.5-ft

8.5-ft

8.5-ft

8-ft

10-ft


Damage Containment & Mitigation

8-ft

10-ft

8.5-ft

8.5-ft


Air Containment Concepts

Tough exoskeleton of woven polyester webbing

Inner shell of elastomer coated fabric

Primary air containmentbladder


Summary

• LMCS 1/12th scale model tests provided:– Useful insights into flotation characteristics– An empirical data base for comparison with analytical models– Confirmation of pressure/stiffness relationship of strap constrained

LMCS platform concept

• Geometry study confirms deeper platform can meet buoyancy/freeboard requirements

• Pressure bag failure modes analysis is ongoing exploring:– Puncture resistance using multi-layered containment system– Secondary (i.e backup) bladders– Foam filled for specific applications

lightweight modular causeway section (lmcs) research & development for tsv applications

Documents

stability characteristics

inches water

lmcs concepta payload

water gauge

float d vented

floatation characteristics

float afloats

inches highweights