FACULTY OF ENGINEERING & ARCHITECTURE
Digital Image Correlation
Technique Applied to
Laminated Glass Plates Under
Free Air Blast Loading
Sam Van Dam
1, Joren Pelfrene
1& Wim Van Paepegem
1Bachir Belkassem
2& David Lecompte
2Outline
...
•
Introduction
•
Experimental setup
‣
Instrumentation
•
Post-processing & Results
‣
DIC
•
Increased use laminated glass
•
Wingard
‣
Design software
•
ASTM Standards
‣
Witness panel
‣
Limited instrumentation
Introduction
...
•
Increase knowledge mechanical response
•
Widely instrumented tests
‣
High dynamic loading – Digital Image Correlation
•
Finite Element Analysis
Validated numerical framework
•
Laboratory of Analysis of Explosion Effects (LAEE) RMA
‣
Steel mounting frame
‣
Specimen size 0.4 by 0.4 m
‣
Clamping ring, felt
‣
2 high speed camera’s
‣
Instrumentation
Blast setup
...
•
Composition C4
‣
Imperfect spherical shape
•
Detonator
‣
Type M75, 1g TNT eq.
•
Light intensity trigger
•
Blast pencil
Digital Image Correlation setup
...
•
2 Photron Fastcam SA5
•
25.000 fps
•
Shutter 1/40.000 s
•
512 x 512 pixels
•
4 light spots
•
Correlated Solutions
VIC 3D
Instrumentation
...
•
Laser doppler vibrometer
•
High shock accelerometer
•
Strain gauges
•
(Blast pencil)
Specimens
...
•
Laminated glass
•
400 x 400 mm
•
t
glass
4 mm nominal
•
t
PVB
0.76 mm
•
t
PVB
0.38 mm
BLACK
Specimens
...
•
Speckle pattern
•
Optimized 512 x 512 pixels
Results – Blast pencils
...
•
Reflections due to nearby wall and floor
-100 0 100 200 300 400 500 600 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Incid ent p res sure [ kP a] Time [ms]
•
Shockwave reaches cameras after ~7 ms
•
Loss of calibration
•
175 undisturbed images
Results – Blast pencils
...
-4 -2 0 2 4 6 0 2 4 6 8 10 12 Incid ent p res sure [ kP a] Time [ms]
•
Reflection due to curvature glass
Results – DIC
...
•
Elastic response reproducible
•
Large scatter afterwards
-30 -20 -10 0 10 20 30 40 50 0 3 6 9 12 15 Displace men t [mm ] Time [ms]
Centre displacement, 30 gr - 30 cm
Results – DIC
...
ε
1
ε
2
Results – DIC
...
Results – DIC
...
Results – DIC
...
•
Crack opening hardly visible
•
Correlation software correlates ‘over’ cracks
•
Strains too large for glass
•
Future test campaign with smaller speckle size
Conclusions
...
•
Widely instrumented test setup
•
Large scatter due to brittle material glass
‣
Comparison different parameters made difficult
Thank you for your attention !
Any questions, remarks ?
SAM VAN DAM
EA10 Materials Science and Engineering
Ghent University, Belgium
