SAMPE Journal - May/June 2020 - 49
EXPERIMENT
A cured composite laminate sample was examined using close-proximity flash thermography
and large-standoff step thermography systems to
compare the signal-to-noise (SNR) performance of
the two systems. Experiments were performed on
a carbon fiber-epoxy test panel with dimensions
30.5mm x 15.2mm x 4mm constructed of twill
weave outer plies and uniaxial inner plies, oriented
0 and ±90. The tow width of the outer plies was approximately 1.6mm.
Flat bottom hole (FBH) defects with diameters
25.4mm, 19.1mm, 12.7mm, 6.4mm, and 2.2mm
were programmed into the sample at depths of
1.5mm, 2.3mm, and 3.0mm. Layout of the holes are
shown in Figure 3, with aspect ratio descriptions
given in Table 1. The sample was inspected in "as is"
condition, i.e. no surface preparation was applied.
Close-Proximity Flash Thermography
The sample was evaluated using a commercial
flash thermography system with 2 quartz-xenon
linear flash lamps, housed in a reflective hood14.
Each lamp is mounted in a reflector and driven by
a 6 kJ power supply that provides a truncated rectangular optical pulse with variable duration ranging from 10msec to 200 microseconds. The system
employs a 640 x 480 pixel InSb camera operating
in the 2-5 micron spectral range at a maximum
full frame rate of 120 Hz. Digital data from the
camera is transferred to a PC in real-time, and the
temperature-time sequence immediately before,
during, and after flash heating is processed using
TSR on each pixel in a dedicated software program
that displays the reconstructed signal, as well as its
1st and 2nd logarithmic derivatives and various attributes of the derivatives, including the Max and
Sum SRC Images.
The sample was place 12" from the camera lens
and lamps, providing a spatial resolution of 2.1 px/
mm, and heated with a 3msec duration rectangular flash pulse. Data was acquired for 83 msec prior
to the flash pulse and for 59.91 seconds after, at a
frame rate of 120 Hz. Images of both the raw and
TSR second derivative results are presented in Figure 4.
w w w. s a m p e . o r g
Figure 3. 4mm thick CFRP test panel with programmed FBH defects of diameters 25.4mm, 19.1mm, 12.7mm, 6.4mm, and 2.2 mm at depths of 1.5mm,
2.3mm, and 3.0mm.
Table 1. FBH defect aspect ratios present in test sample.
Aspect
Ratio
Diam [mm]
The SRC is calculated for every pixel and every frame in the image sequence, resulting in a 3D
matrix of SRC values, which can be interrogated
through the time axis to yield single image maps of
the maximum SRC, the sum of SRC or the time at
which the SRC occurs for every pixel.
25.4
19.1
12.7
6.4
2.2
1.5
16.7
12.5
8.3
4.2
2.1
2.3
11.1
8.3
5.6
2.8
1.4
3.0
8.3
6.25
4.2
2.1
1.0
Depth [mm]
Figure 4. Raw (left) and TSR Second Derivative (right) images generated
using the close-proximity flash thermography experimental setup.
M AY/J U N E 2 0 2 0
|
SAMPE JOURNAL
|
49
http://www.sampe.org
SAMPE Journal - May/June 2020
Table of Contents for the Digital Edition of SAMPE Journal - May/June 2020
Table of Contents
SAMPE Journal - May/June 2020 - Cover1
SAMPE Journal - May/June 2020 - Cover2
SAMPE Journal - May/June 2020 - Table of Contents
SAMPE Journal - May/June 2020 - 2
SAMPE Journal - May/June 2020 - 3
SAMPE Journal - May/June 2020 - 4
SAMPE Journal - May/June 2020 - 5
SAMPE Journal - May/June 2020 - 6
SAMPE Journal - May/June 2020 - 7
SAMPE Journal - May/June 2020 - 8
SAMPE Journal - May/June 2020 - 9
SAMPE Journal - May/June 2020 - 10
SAMPE Journal - May/June 2020 - 11
SAMPE Journal - May/June 2020 - 12
SAMPE Journal - May/June 2020 - 13
SAMPE Journal - May/June 2020 - 14
SAMPE Journal - May/June 2020 - 15
SAMPE Journal - May/June 2020 - 16
SAMPE Journal - May/June 2020 - 17
SAMPE Journal - May/June 2020 - 18
SAMPE Journal - May/June 2020 - 19
SAMPE Journal - May/June 2020 - 20
SAMPE Journal - May/June 2020 - 21
SAMPE Journal - May/June 2020 - 22
SAMPE Journal - May/June 2020 - 23
SAMPE Journal - May/June 2020 - 24
SAMPE Journal - May/June 2020 - 25
SAMPE Journal - May/June 2020 - 26
SAMPE Journal - May/June 2020 - 27
SAMPE Journal - May/June 2020 - 28
SAMPE Journal - May/June 2020 - 29
SAMPE Journal - May/June 2020 - 30
SAMPE Journal - May/June 2020 - 31
SAMPE Journal - May/June 2020 - 32
SAMPE Journal - May/June 2020 - 33
SAMPE Journal - May/June 2020 - 34
SAMPE Journal - May/June 2020 - 35
SAMPE Journal - May/June 2020 - 36
SAMPE Journal - May/June 2020 - 37
SAMPE Journal - May/June 2020 - 38
SAMPE Journal - May/June 2020 - 39
SAMPE Journal - May/June 2020 - 40
SAMPE Journal - May/June 2020 - 41
SAMPE Journal - May/June 2020 - 42
SAMPE Journal - May/June 2020 - 43
SAMPE Journal - May/June 2020 - 44
SAMPE Journal - May/June 2020 - 45
SAMPE Journal - May/June 2020 - 46
SAMPE Journal - May/June 2020 - 47
SAMPE Journal - May/June 2020 - 48
SAMPE Journal - May/June 2020 - 49
SAMPE Journal - May/June 2020 - 50
SAMPE Journal - May/June 2020 - 51
SAMPE Journal - May/June 2020 - 52
SAMPE Journal - May/June 2020 - 53
SAMPE Journal - May/June 2020 - 54
SAMPE Journal - May/June 2020 - 55
SAMPE Journal - May/June 2020 - 56
SAMPE Journal - May/June 2020 - 57
SAMPE Journal - May/June 2020 - 58
SAMPE Journal - May/June 2020 - 59
SAMPE Journal - May/June 2020 - 60
SAMPE Journal - May/June 2020 - 61
SAMPE Journal - May/June 2020 - 62
SAMPE Journal - May/June 2020 - 63
SAMPE Journal - May/June 2020 - 64
SAMPE Journal - May/June 2020 - 65
SAMPE Journal - May/June 2020 - 66
SAMPE Journal - May/June 2020 - 67
SAMPE Journal - May/June 2020 - 68
SAMPE Journal - May/June 2020 - Cover3
SAMPE Journal - May/June 2020 - Cover4
https://www.nxtbook.com/nxtbooks/sampe/journal_20241112
https://www.nxtbook.com/nxtbooks/sampe/journal_20240910
https://www.nxtbook.com/nxtbooks/sampe/journal_20240708
https://www.nxtbook.com/nxtbooks/sampe/journal_20240506
https://www.nxtbook.com/nxtbooks/sampe/journal_20240304
https://www.nxtbook.com/nxtbooks/sampe/journal_20240102
https://www.nxtbook.com/nxtbooks/sampe/journal_20231112
https://www.nxtbook.com/nxtbooks/sampe/journal_20230910
https://www.nxtbook.com/nxtbooks/sampe/journal_20230708
https://www.nxtbook.com/nxtbooks/sampe/journal_20230506
https://www.nxtbook.com/nxtbooks/sampe/journal_20230304
https://www.nxtbook.com/nxtbooks/sampe/journal_20230102
https://www.nxtbook.com/nxtbooks/sampe/journal_20221112
https://www.nxtbook.com/nxtbooks/sampe/journal_20220910
https://www.nxtbook.com/nxtbooks/sampe/journal_20220708
https://www.nxtbook.com/nxtbooks/sampe/journal_20220506
https://www.nxtbook.com/nxtbooks/sampe/journal_20220304
https://www.nxtbook.com/nxtbooks/sampe/journal_20220102
https://www.nxtbook.com/nxtbooks/sampe/journal_20211112
https://www.nxtbook.com/nxtbooks/sampe/journal_20210910
https://www.nxtbook.com/nxtbooks/sampe/journal_20210708
https://www.nxtbook.com/nxtbooks/sampe/journal_20210506
https://www.nxtbook.com/nxtbooks/sampe/journal_20210304
https://www.nxtbook.com/nxtbooks/sampe/journal_20210102
https://www.nxtbook.com/nxtbooks/sampe/journal_20201112
https://www.nxtbook.com/nxtbooks/sampe/journal_20200910
https://www.nxtbook.com/nxtbooks/sampe/journal_20200708
https://www.nxtbook.com/nxtbooks/sampe/journal_20200506
https://www.nxtbook.com/nxtbooks/sampe/journal_20200304
https://www.nxtbook.com/nxtbooks/sampe/journal_20200102
https://www.nxtbook.com/nxtbooks/sampe/journal_20191112
https://www.nxtbook.com/nxtbooks/sampe/journal_20190910
https://www.nxtbook.com/nxtbooks/sampe/journal_20190708
https://www.nxtbook.com/nxtbooks/sampe/journal_20190506
https://www.nxtbook.com/nxtbooks/sampe/journal_20190304
https://www.nxtbook.com/nxtbooks/sampe/journal_20190102
https://www.nxtbook.com/nxtbooks/sampe/journal_20181112
https://www.nxtbook.com/nxtbooks/sampe/journal_20180910
https://www.nxtbook.com/nxtbooks/sampe/journal_20180708
https://www.nxtbook.com/nxtbooks/sampe/journal_20180506
https://www.nxtbook.com/nxtbooks/sampe/journal_20180304
https://www.nxtbook.com/nxtbooks/sampe/journal_20180102
https://www.nxtbook.com/nxtbooks/sampe/journal_20171112
https://www.nxtbook.com/nxtbooks/sampe/journal_20170910
https://www.nxtbook.com/nxtbooks/sampe/journal_20170708
https://www.nxtbook.com/nxtbooks/sampe/journal_20170506
https://www.nxtbook.com/nxtbooks/sampe/journal_20170304
https://www.nxtbook.com/nxtbooks/sampe/journal_20170102
https://www.nxtbook.com/nxtbooks/sampe/journal_20161112
https://www.nxtbook.com/nxtbooks/sampe/journal_20160910
https://www.nxtbook.com/nxtbooks/sampe/journal_20160708
https://www.nxtbook.com/nxtbooks/sampe/journal_20160506
https://www.nxtbook.com/nxtbooks/sampe/journal_20160304
https://www.nxtbook.com/nxtbooks/sampe/journal_20160102
https://www.nxtbook.com/nxtbooks/sampe/journal_20151112
https://www.nxtbook.com/nxtbooks/sampe/journal_20150910
https://www.nxtbook.com/nxtbooks/sampe/journal_20150708
https://www.nxtbook.com/nxtbooks/sampe/journal_20150506
https://www.nxtbook.com/nxtbooks/sampe/journal_20150304
https://www.nxtbook.com/nxtbooks/sampe/journal_20150102
https://www.nxtbook.com/nxtbooks/sampe/journal_20141112
https://www.nxtbook.com/nxtbooks/sampe/journal_20140910
https://www.nxtbook.com/nxtbooks/sampe/journal_20140708
https://www.nxtbook.com/nxtbooks/sampe/journal_20140506
https://www.nxtbook.com/nxtbooks/sampe/journal_20140304
https://www.nxtbook.com/nxtbooks/sampe/journal_20140102
https://www.nxtbook.com/nxtbooks/sampe/journal_20131112
https://www.nxtbook.com/nxtbooks/sampe/journal_20130910
https://www.nxtbook.com/nxtbooks/sampe/journal_20130708
https://www.nxtbook.com/nxtbooks/sampe/journal_20130506
https://www.nxtbook.com/nxtbooks/sampe/journal_20130304
https://www.nxtbook.com/nxtbooks/sampe/journal_20130102
https://www.nxtbook.com/nxtbooks/sampe/journal_20121112
https://www.nxtbook.com/nxtbooks/sampe/journal_20120910
https://www.nxtbook.com/nxtbooks/sampe/journal_20120708
https://www.nxtbook.com/nxtbooks/sampe/journal_20120506
https://www.nxtbook.com/nxtbooks/sampe/journal_20120304
https://www.nxtbook.com/nxtbooks/sampe/journal_20120102
https://www.nxtbook.com/nxtbooks/sampe/journal_20111112
https://www.nxtbook.com/nxtbooks/sampe/journal_20110910
https://www.nxtbook.com/nxtbooks/sampe/journal_20110708
https://www.nxtbook.com/nxtbooks/sampe/journal_20110506
https://www.nxtbook.com/nxtbooks/sampe/journal_20110304
https://www.nxtbook.com/nxtbooks/sampe/journal_20110102
https://www.nxtbookmedia.com