Hypervelocity Impact Overarching Experimental Challenge: Experimental Measurement of G

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Hypervelocity Impact Overarching Experimental
Challenge Experimental Measurement of G
Leslie Lamberson, Jonathan Mihaly,
Professor Ares Rosakis, Caltech, Dr. Marc Adams
(JPL)
PSAAP Site Visit October 28th, 2009
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The Experiment
Hypervelocity Impact a HIGH ENERGY DENSITY
EVENT
Important Physics
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The Experimental Facility
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
Launch Package Examples
Mylar Burst Disk
3 mil (1x103 in) thick 11/16 diameter
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
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Facility
TARGET TANK
PUMP TUBE
LAUNCH TUBE
FLIGHT TUBE
BREECH
STAGE 1
STAGE 2
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PSAAP Experiment Impactor Target
Front Spall Cloud
Debris Cloud

• Impactor
• Material (SS, Ta, nylon)
• Speed (V)
• Size

Witness Plate/Capture Media

• Target
• Material (SS, Ta)
• Thickness (h)
• Impact Obliquity (a)

Controllable Input Parameters
Current Experiment Results (output)

• Target material
• Target thickness (h)
• Impact Obliquity (a)
• Impact Mass (m)
• Impact Material

• Impact Velocity (V)
• Target Deformation
• Perforation Area (A)
• Ejecta characterization

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Typical Experimental Configuration
Witness Plate
Target
aluminum witness plates replaced by capture media
Impactor

• Target Materials
• Steel
• Aluminum
• Tantalum

Ø 71 mil (1x10-3 in) launch tube bore

• Impactor Materials
• Steel
• Nylon
• Aluminum
• Tantalum

• Impact Speeds 2 to 10 km/s
• Impact Obliquities 0 to 80 degrees
• Impactor Mass 1 to 50 mg

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SPHIR Experiment Demonstration

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The Experimental FacilityGun Performance
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The Experimental FacilityGun Performance
SPHIR smooth-bore design maximizes launch
package velocity but prevents use of conventional
sabot technology
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The Experimental FacilityGun Performance
New sabot technology must be developed to launch
small SS Ta spheres to ultra high velocities
?10km/s

• Objectives
• Achieve impact speed - 10 km/s
• Clean launch (only impactor hits target)
• Accurate launch
• Reliable launch

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Velocimetry Method 2 4 km/s

• Impact speed determined from time of flight
  between mylar sheet and target
• Target and mylar 0.60 m apart
• Mylar 12.7 mm thick (min effect on impactor)
  

2D Static Side View
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Capturing Impact Velocity 2 4 km/s
Launch Package 440 C Steel Sphere L/D 1, D
1.8 mm, M 24 mg H2 Pressure 150 psi Vacuum
15 Torr
Target 304 Stainless Steel 150 x 150 x 2.7
mm 0º Obliquity Shot Velocity 2.5 km/s
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Capturing Impact Velocity 4 km/s
Launch Package Nylon Slug L/D 1, D
0.070 H2 Pressure 150 psi Vacuum 1 Torr
Target 304 SS, 6x6x0.073 0 Obliquity
Shot Velocity 6.0 km/s
Higher velocities (V gt 4 km/s) produce streak

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SPHIR Optical Diagnostics

• Analysis in Transmission
• to understand materials under hypervelocity
  impact induced dynamic behavior

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Optical Methodologies I
Mylar 1.5 MPa

• Caustics - Transmission

CAUSTIC
CRACK
D
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Optical Methodologies II

• Dynamic Photoelasticity

Isochromatic Fringe Data
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Experimental Configuration

• Birefringent Materials Mylar Homalite100
• Tension Loads 0.5 4 MPa
• Impact Speeds 3-6 km/s

Optical distortions removed from images for
analysis in MATLAB via control point selection
using the image toolbox
(Above) Optical Path (Right) Target loaded in
tension with collimated laser light illumination
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Homalite 100 In-situ Behavior
Unloaded
Loaded 3.75 MPa, Circular Hole
Nylon Slug, Impact Velocity 5.5 km/s
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General Behavior HOMALITE 100

• Brittle behavior Extent of crack growth depends
  on pre-load, stress concentration, hypervelocity
  impact speed, and relation of impact site to
  stress concentration
• Lower crack tip speeds (lt300 m/s) result in crack
  growth during wave reflections and interactions
• KINKED FRACTURE SURFACE

Impact Site
(1)

• 3.75 MPa pre-load, multiple crack propagation
  sites (with branching), 5.7 km/s impact

(2)
(2) 1.8 MPa pre-load, 5.9 km/s impact
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Mylar In-situ Behavior
Unloaded
Loaded 3.75 MPa, Pre-crack
Nylon Slug, Impact Veloctiy 5 km/s (left), 4.5
km/s (right)
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General Behavior - Mylar

• Extensive crack growth beyond impact location
  exhibited only under pre-loaded (tension)
  conditions
• Under pre-load, if hypervelocity impact location
  was within approximately 1 diameter of the
  pre-stress concentration location, cracks would
  propagate from the concentration location instead
  of impact site
• High crack tip speeds (gt 500 m/s) allow cracks to
  more closely follow initial dilatational waves
  from impact
• FLAT FRACTURE SURFACE

(1)
(2)

• Loaded before impact (no stress concentration)
• 100 µs after impact at 4.7 km/s

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Instrumentation - Conoscope

• Conoscope
• VISAR
• CGS (in situ)
• Backlighting
• Spectroscopy

• Optimet MiniConoscan 3000
• highest resolution available (microns) laser
  reflectance profilometer
• Scans 4 x 4 area with 6-10 mm precision in x,
  y, z
• Produces surface map as x,y,z coordinate table

Metric Provided to Analysts Accurately measured
post-test target deformation features for
comparison with numerical simulation

• G Data Provided
• Target Perforation area
• Post-test slope map (Surface Slope f(x,y)

Delivery Nov 2009 Operational Dec 2009 PSAAP
Data Collection Dec 2009
Image courtesy of Optimet Optical Metrology
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Image courtesy of Optimet Optical Metrology
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Conoscope Performance Measure
Previously used microscope images to create mask
of perforated area
Conoscope improves uncertainty of measurement and
allows flexibility in selecting measured quantity
1/32
x,y,z
MiniConoscan Image courtesy of Optimet Optical
Metrology
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Conoscope Performance Measure
Replicated tests have exhibited large scatter in
the perforation area
Consider area interior to defined critical
height/slope?
x,y,z
MiniConoscan Image courtesy of Optimet Optical
Metrology
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Instrumentation - VISAR
Continuous Measurement of Target Surface
Velocity at selected points during impact

• Conoscope
• VISAR
• CGS (in situ)
• Backlighting
• Spectroscopy

• High temporal definition (entire impact event
  with lt1 ms resolution)
• Limited spatial resolution (data taken at 4
  points, can be expanded to 7)

Metric Provided to Analysts Normal surface
velocity of entire deformation event at 4
selected points with high lt1 ms resolution
Valyn Multi-Beam VISAR
Delivery Feb 2010 Operational Mar 2010 PSAAP
Data Collection May 2010
Image courtesy of Valyn
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Instrumentation - CGS
Continuous Measurement of Full-field Target
Surface Slope in X and Y directions during impact

• Conoscope
• VISAR
• CGS (in situ)
• Backlighting
• Spectroscopy

• Limited temporal definition (8 selectable
  camera exposure times from ns to ms)
• High spatial resolution (entire target)

Metric Provided to Analysts Contour maps of
entire target describing slope in x and y
directions at 8 selectable times
Coherent Gradient Sensing (CGS)

• currently have post mortem CGS capability

Delivery Jan 2010 Operational Jun 2010 PSAAP
Data Collection Aug 2010
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Post-mortem CGS

• Surface slope maps utilizing a shearing
  interferometry technique Coherent Gradient
  Sensing (CGS)

Interferogram Digitized Slope Map
Sample CGS results, 304 stainless steel disc 10
mm thick, nylon cylindrical slug 2 mm length L/D
1, Stern (rear side), impact velocity 5.5 km/s,
un-penetrated target

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Post mortem CGS II

• 3-D topological deformation mapping of
  post-impacted specimen

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Instrumentation - Back Lighting

• Continuous imaging of entire impact event in 5ns
  to 1 ms intervals

• Conoscope
• VISAR
• CGS (in situ)
• Backlighting
• Spectroscopy

Metric Provided to Analysts Continuous
silhouette images (5ns to 1ms) resolution of
impact event with collimated laser or white light
Flashlamp /or Collimnated Laser
Delivery Jan 2010 Operational Sep 2010 PSAAP
Data Collection Oct 2010
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