Numerical Modeling of Wave Propagation in Particulate ...
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Modeling of Wave Propagation in Particulate Composites Phani Mylavarapu, Srivathsa Boddapati Defence Metallurgical Research Laboratory, Kanchanbagh 1 17-11-2011
Transcript of Numerical Modeling of Wave Propagation in Particulate ...
Modeling of Wave Propagation in Particulate
Composites
Phani Mylavarapu, Srivathsa Boddapati
Defence Metallurgical Research Laboratory,
Kanchanbagh
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Outline • Introduction • Problem Definition • FEM Modeling • Approach • Results and Discussions • Conclusions and Future work
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Syntactic foams (SF)
Two phase Three phase
microballoons
matrix
void
SEM Image of Syntactic Foams
ηi= ri/ro
t d0
Underwater explorer
Courtesy: Oceanexplorer 3 17-11-2011
Ultrasonic Testing
• Attenuation
• Ultrasonic Velocity – Longitudinal Velocity (𝑉𝑙) – Shear Velocity (𝑉𝑠)
E. Segal and J. L. Rose, in: Research Techniques in Non-Destructive Testing, Vol. IV,R. S. Sharpe (Ed.), pp. 275–316. Academic Press, London (1980).
xeA
A 0
ras
2* lVL 2* sVG GL
GLGE
)43(
)(22GL
GL
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Modulus Predicted from UT Sample Name
Predicted UI Modulus, MPa
SHPB Modulus, MPa
Quasi -Static Modulus,
Mpa
Pure Epoxy 4476±183 4272-5084 2320±40
S2210 3667±89
3310-3903 2156
S2250 2173±41
1701-2244 1512
S3210 4071±45
3048-4099 2310
S3250 2800±88
2146-2808 2052
S3840 3481±25
3244-3664 2351
K4650 3385±109
2901-3446 2473
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Cluster Interaction With Ultrasonic Energy
Problems with Ultrasonic Testing
• Difficult to distinguish the reflections originating from epoxy or particle or epoxy/particle interface
• Waves due to multiple reflections
S2230
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0 5000 10000 15000 20000 25000 30000 35000
Time, ns
Am
pli
tud
e, V
olt
s
First back
wall reflection Second back
wall reflection Third back
wall reflection
Front wall reflection
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1a
1a
1a
Typically UT performed
& Experimentally difficult
Modeling using COMSOL
• BC’s available for source of excitation: – Gaussian point source – Pressure – Plane wave radiation
• BC’s available for reflection/transmission between interfaces – Impedance
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Qcp
pqp
p oo
2
21. 01
qpn t
Sound Hard Boundary
t
p
zqpn t
i
t
11.
Mesh Details and CFL • 0.285 element size • ƛ/10 • Same element size for all models • CFL Criteria: 5e-9 s
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Case 1: 1a
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Case 1 (contd…)
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Case 1 (contd…)
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Case 1 (contd…)
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1a
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Comparison of pressure in the particle
1a
1
a
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1a
Conclusions and Future Work • Effect of ratio of wavelength to particle size on
reflection studied. • Ratios of less than, greater than and equal to 1. • Multiple reflections from particles
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Acknowledgements
• Director, DMRL • Dr. Nikhil Gupta, Brooklyn University
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