Transcript Center for Structures in Extreme Environments

Center for Structures in Extreme
Environments
M E C H A N IC A L & A E R O SP A C E
Haym Benaroya, [email protected]
MAE Open House SoE
12 March 2008
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Research Focus of Center
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•
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• Structural modeling
Offshore structures
• Force modeling
Aircraft structures
• Uncertainties
Lunar and Martian
definition
structures
• Reliability and life
Nanostructures
estimates
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Disciplinary Focus of Center
Primary
• structural dynamics
& environmental modeling
• multi-disciplinary engineering
Secondary
• economics and finance
• policy
• sociology
• psychology
M E C H A N IC A L & A E R O SP A C E
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Nonlinear Nanoresonator Dynamics: Sensors & Mechanisms
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Research Focus of Center
Aircraft structures
M E C H A N IC A L & A E R O SP A C E
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Aircraft Structures
Small fuselage section
between consecutive frames
and stringers (SP)
Panel of an LD-3 luggage
container (LP)
SP: Al 2024-T3 20 x 8 x 0.063 in
LP: Al 7021-T6 59 x 57.5 x 0.16 in
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Example of Box Shaped Model I
LD-3 luggage container
after internal bomb blast

2.01 m x 1.57 m x 4 mm (Panel III)

1.53 m x 1.63 m x 4 mm (Panel IV)

Clamped Al 7021-T6 Plate
Pressure loading of
Fleisher (1996)
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Elastic Deformation Pattern
Elastic sinusoid
deformation pattern
Assumed form of elastic
plate deflection
Clamped plate SDOF equation of motion
General form of yield criterion
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Plastic Deformation Pattern
Analytical idealization of
experimental profile
Experimental deformation profile
of Jones et al. (1970)
 All energy is dissipated in the
edges and five plastic hinges.
General equation of motion
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Smaller Panel Standard
Deviation Bounds
100
400
80
Critical Deflection
60
40
Maximum Deflection (mm)
Maximum Deflection (mm)
350
300
250
200
150
100
20
0.3
Critical Deflection
0.4
0.5
0.6
0.7
0.8
0.9
Standoff Distance (m)
Mean deflection of SP
subjected to SC with bounds
1
50
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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Standoff Distance (m)
Mean deflection of SP
subjected to LC with bounds
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Larger Panel Standard
Deviation Bounds
700
120
Maximum Deflection (mm)
Maximum Deflection (mm)
600
100
80
60
500
400
300
Critical Deflection
200
40
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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Standoff Distance (m)
Mean deflection of LP subjected
to SC with bounds
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Standoff Distance (m)
Mean deflection of LP subjected
to LC with bounds
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Probability of Failure
1
Probability of Failure
0.8
LC/LP
0.6
SC/SP
0.4
0.2
0
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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• Monte Carlo method can
also be used to estimate the
probability of structural
failure.
• Based on maximum strain
criterion.
• All failures for LC/SP
case.
• No failures for SC/LP case.
Standoff Distance (m)
Probability of failure for SC/SP and
LC/LP cases
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Research Focus of Center
Lunar and Martian
structures
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Extraterrestrial Structures
Extraterrestrial structures such as those
appropriate for the Moon and Mars present
added difficulties due in part to:
• the lack of atmosphere
• the large distance from safety
• often intense radiation
• micrometeorites
• extreme temperatures and temperature
fluctuations
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Structural Design of a Lunar Base
Base Layout
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Research Focus of Center
Offshore structures
M E C H A N IC A L & A E R O SP A C E
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Heidrn Platform
Using a technologically innovative
compliant tower, the Baldpate Field,
on Garden Banks 259/260, was brought
on stream in 1998.
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Equatorial Guinea
• The Okume Complex is comprised of the
Okume, Oveng, Ebano and Elon fields
which have been developed using a
combination of two tension leg platforms
and four fixed platforms.
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Norway’s Valhall field
Denmark's South Arne
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Tension Leg Platform (TLP)
Pontoon
Risers
}
Platform
Column
Deck
Tendons
Foundation
template
Ram-Powel TLP in Gulf of Mexico
(built in 1997 in 3,214 ft of water)
Schematic of a TLP
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Schematics of Compliant Towers
Articulated Tower
Tension Leg Platform
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Coupled Axial and Transverse Vibration with End
Tension
X
Tension Ft(x,t)
M
Mean Water Level
• Tower has two degrees of freedom
Y(x,t)
• Tower is extensible
Buoyancy
Forces
• The tower has a Tension applied at
the free end
L
d
• In-plane fluid force is approximated
by the Morison equation.
Gravity
Forces
Y
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Vortex-Induced Oscillations: Analysis and Experiments
“Inverted Pendulum Model”
• Hollow aluminum tube
attached by a leaf spring.
• d = 2.54 cm; l = 128 cm
• Mass ratio = 1.53
1" (Diameter)
• Damping ratio = 0.054
• fn = 1.25 Hz
• Motion restricted to the
cross stream plane
• Deflection; qmax ≈ 1.1°
48" (Length)
Flow
Direction
z
x
y
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In Closing:
Celebration after Rutgers upsets
#3 Louisville 28-25 on 11/9/06
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