1. Thermophysical Laboratory
BABOU Amine
EADS CRC France
SERVICE DCR/MP/MC
Thermophysical Laboratory
Thermal characterisation of an UD carbon fibre / epoxy composite
Methods of characterisation
-Thermal conductivity direct measurement in plane X, Y « hot guarded plates »
-Thermal diffusivity through thickness « Flash »
-Thermal capacity « D.S.C. »
-Thermal diffusivity in plane X,Y « Thermography »
Results

2. F With F = U * I = FT + FL FT = Transmitted flow FL = Lost flow
e = sample thickness ( 5 to 28mm )
S = sample section ( 25mm diameter ) T1 Tc
Sample
Thermic well F
U, I
Cold plate T2 Th
Hot plate
l = U * I * e / S* [(T12-T22) + [(T11-T21)]
CONDUCTIVITY « Hot garded plates » METHOD
The method consists in measuring the necessary heat flow ( F ) to maintain one difference
of temperature about 10°C between the two faces of the test specimen.
First condition « adiabatic » Th = Tc
FL = l * S * ( T11-T21 ) / e
Second condition Th = Tc + 10°C
F = U * I = l * S * (T12-T22) / e
Conductivity determination with:

3. TEST SPECIMEN PREPARATION FOR IN PLANE CONDUCTIVITY MEASUREMENT
F=25mm, h=28mm
Cube of 30*30*30 mm3
Obtained by sticking
Direction of measurement
Composite panel X Y

4. between the measured signal and the calculated signal.
DIFFUSIVITY 1D ALONG Z « Flash » METHOD
The method consists in imposing a dirac of energy on a face of the test specimen and
to measure on the other face the temporal distribution of the temperature.
Thermal diffusivity is determined with a thermal model by making the comparison
between the measured signal and the calculated signal.
Lens
Infrared detector
Laser 90j/ 350ms
Sample
Diffusivity calculation
Losses thermic flow calculation
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8 5 10 15 20 25 30 35
t (s)
T red
Increasing expérimental thermogram
0,2
0,4
0,6
0,8 1
1,2 10 20 30 40 50 60 70
t (s)
T red
Decreasing expérimental thermogram

5. Expérimental thermogram
Calculated thermogram
instataneus diffusivity

6. CAPACITY «Differential Scannig Calorimeter » METHOD
The method consists in measuring the difference of heat flow ( DW ) to maintain the sample in the same conditions as the reference. -
Référence
Sample DW
T(°C)
D. S. C.
CpS = ( DW / V* mS) + ( mS x Cpr / mr)
With V = dT / dt temperature kinetics
mS = sample weight
mr = reference weight
Cpr = reference capacity

7. DIFFUSIVITY ALONG X AND Y 2D « Flash » METHOD
The method consists in imposing a dirac of energy in the center of a face of the test specimen and to measure at any time on the other face the spatial distribution of the temperature. Thermal diffusivity is determined with a 2D thermial model.
Laser 90j / 350 ms
IR Camera X Y
Sample

8. ( ) Fourier transformation ² , ln t a - ÷ ø ö ç è æ = q
Picture at t1
Picture at t2
Average along Y axis at t1
Average along Y axis at t2 X Y T
Fourier transformation ) ( 1 2 , ln t a x - ÷ ø ö ç è æ = q
ax identification

9. TECHNICAL SPECIFICATION OF EQUIPMENTS

10. MATRIXES OF RESULTS
Calcul. l = « a » * « r » * « Cp »