212
6-83 B and C). The first result shown in Figure 6-83 A was obtained by normalizing the
series of thermal images using the initial slope of the temperature vs. t1/2 response. The
second result (Figure 6-83 B) was obtained by applying a least squares sinusoidal curve
fit to temperature vs. time data and examining the phase response. The final result,
Figure 6-83 C, was obtained by applying a discrete Fourier transform to the data
collected during cooling. All three results are very similar. Most importantly, the results
are independent of the intensity of the heat flux that was used to heat the surface.
14
A B
t 3
15
010
C
Figure 6-83. Comparison of data analysis techniques for Specimen A-3. A) Normalized
temperature result at t = 160 sec. B) Lock-in results for pulse duration =
250 sec. C) Pulse phase result at f = 0.0083 Hz.
Series B, C, D, and E Specimens
The specimens in Series B, C, D, and E were constructed to investigate the effects
of the following FRP system properties on IRT results: