Marc Adams (JPL), Experiment - Caltech PSAAP

The Experimental Effort
Hypervelocity Impact Phenomena:
Measurement of “G”
Dr. Marc Adams, Caltech/JPL, Jonathan Mihaly,
Professor Ares Rosakis, Caltech
V&V UQ Workshop
July 28 - 30, 2009
PSAAP: Predictive Science Academic Alliance Program

Presentation
•The Experiments
•Interactions between Experimental & Computational Efforts
•The Experimental Facility
•Basic Test Configuration
•Gun Performance
•Measurement of Test Result (Perforation Area)
•Test Results to Date
•Semi-empirical Model of Perforation Area
•Strategy for Instrumentation Development
•SPHIR Facility Upgrades
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The Experiments
Impactors
•Material (SS, Ta)
•Speed (V)
•Size
• Impact Speeds: 2 to 10 km/s
• Impact Obliquities: 0 to 80
degrees
• Impactor Mass: 1 to 50 mg
Currently
measuring
perforation
area
Front
Spall
Cloud
Target
•Material (SS, Ta)
•Thickness (h)
Debris
Cloud
•Impact Obliquity ()
Capture Media
Future Measurements
•Backlit Debris and Spall Clouds (’09)
•Post-test Permanent Deformation Field of
Target (’09) – Conoscope
• Dynamic (real time) target deformations
with Visar & CGS instruments (’09)
•Spectrometer analyzing spall & debris
clouds (Sprg ’10)
•Capture Media for analysis of Spall &
Debris Clouds (’11)
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The Experimental Facility
Small Particle Hypervelocity Impact Range
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Coupling between Experimental &
Computational Efforts
Interaction Between Experimental Efforts &
the Computation of a UQ Diameter
“G (experimental data) vs. F (numerical simulations)”
Measure A G,
h,
v
Simulate A ave
= F ,
h,
v
Experimental Efforts
Exchanges
Numerical/Computational
Efforts
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Start
Interaction between Experimental &
Computational Efforts (Continued)
Exploratory shots,
e.g. ballistic limit
Instrumentation
development
Test initialization
targets & measure
areas (A)
Test target set &
measure areas
Choose domain of
variables, thickness (h) &
obliquity (α), velocity (v)
random variable
Initialization Target List
i
,
i
h i
i
A G , h , v
A G , h , v
k
k
Iterations
New Target Set
i
k
i
k
i
k
, h
k
k
Select variable for Sub-Diameter
1. Run Impact Simulations,
compute average F (area)
2. Cal c
3. Consider
No
Fj G j
H
Maximum?
Fj G j gradient in
variable space:
define next target set
F j
G j
Yes
Finish
Completed Model Error D FG
No
Completed UQ Sub-Diameter
Remaining variables?
Yes
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The Experimental Facility
Basic Test Configuration
Target Test Setup
Hi Speed Launch Pkg
Impactor 0.9mm Dia.
“Cannon Ball”
1.8 mm Dia.
Sabot
Launch Packages
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The Experimental Facility
Gun Performance
Distribution of Speeds Obtained
Impact Speed (km/s)
10
1
Gun Operating Regime
Current
Plastic
Slugs
Yield from Propellent Burn ~ 3,500J
Goal for
35 mil SS
with sabot
Goal for 35 mil
Ta with Sabot
Current SS
Cannonballs
K.E.
800J
400
200
100
1 10 100
Impactor Mass (mg)
50
Cumulative Probability of Lower Speed
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Fit Errors: Uniform = 0.32 Gaussian = 0.08
Gaussian
Mean = 2.49
StDev = 0.25
1.6 1.8 2 2.2 2.4 2.6 2.8 3
Impact Speed (km/s
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Performance Measure:
Area of Perforation
1. Scan deformed targets
2. Create mask of perforated area
3. Use Image-J software (NIH) to count pixels
4. Convert pixels to
1 pixel =
6.97x10
6
mm
2
2
mm
0.0318”
• Uncertainty in area measure is increased
by out of focus “hanging chad”
• Profilometry measurements using
Conoscope will eliminate problem
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Test Results to Date
12
11
10
9
Data at Various Obliquities between 0 - 30 degrees
h = 1.9mm Data
h = 2.3mm Data
h = 2.6mm Data
Impactor FP area
Perforation Area (mm)
8
7
6
5
4
3
2
Impactor
Footprint Area
1
0
1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
Impact Speed (km/s)
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Semi-Empirical Model of Perforation Area
Perforation Area (mm)
12
11
10
9
8
7
6
5
4
3
2
1
Vbl = Ho*( h/Dp)^n / (cos a)^s
A = if V

Perforation Area Model (h = 2.6mm)
12
10
2.6mm
2.6 Model
26M d l
Perforation Area (mm^2)
8
6
4
0
2
15
0
5 5 10
0
2
4 0
30
15
30
0
0
9
21 5
1.0 1.5 2.0 2.5 3.0 3.5
Impact Speed (km/s)
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Perforation Area Model (h = 2.3mm)
12
10
2.3
2.3 Model
Perforation Area (mm^2)
8
6
4
10
0 15
9
30
11
17
15
23
10
4
20 26 0 0
15 5
23
5
5
30
0
30 18
27
15
21
33
30
2
0
30
1.0 1.5 2.0 2.5 3.0 3.5
Impact Speed (km/s)
20
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Perforation Area Model (h = 1.85mm)
12
10
1.85mm
1.85 Model
0
Perforation Area (mm^2)
8
6
4
0
5
18
5 0
15
40
15
11
15
2
15 30
0
1.0 1.5 2.0 2.5 3.0 3.5
Impact Speed (km/s)
PSAAP: Predictive Science Academic Alliance Program

Strategy for Instrumentation Development
•Background illumination System (’09)
•Continuous imaging of entire impact event
in 1 s intervals
•Conoscope (’09)
•Very accurate measurement of perforation
area & complete characterization of target
deformation
•VISAR & CGS deformation measurements (’09-’10)
•Real time measurement of dynamic target
deformations
•Spectrophotomer (’10)
•Characterization of impact flash and
conditions in debris and spall clouds
•Measurement of emission, absorption &
reflectance spectra over IR to UV range
•Capture Media (’11)
•Characterization of debris & spall clouds
•Particle consistency, size & velocity vector
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Real Time Measurement of
Target Deformation – Two Methods
VISAR
(Velocity Interferometer
System for Any Reflector)
•High temporal definition
•Measure entire deformation
event with 5x10 9 s -1
sampling rate
•Measures up to 4 selected
points on target
Coherent Gradient Sensing (CGS)
•Large area spatial imaging (entire
target)
•Limited temporal resolution
(8 images with selected interframe
times from ns to ms)
Can measure entire deformation field at
8 selected camera exposure times, e.g.
1µs 5µs 10µs 15µs
20µs 30µs 50µs 80µs
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SPHIR Gun Upgrades
•New sabot technology must be developed in order to launch small SS &
Ta Spheres to ultra high velocities ~10km/s
•Achieve impact speed - 10 km/s
•Clean launch - only impactor hits target
•Accurate launch - hit target in desired location
•Reliable launch – most shots successful
Launch Tube
Squeezer
Vapor
Launch Package
Launch Package
(Sabot + Impactor)
Taper
Vaporizes
Sabot
Impactor
flys to
target
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Questions?
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