Composite structures can be laminated to have very low coefficients of thermal expansion. Such structures are light and strong and have many uses where expansion or contraction with temperature change is undesirable. One application is with instruments that measure thermal expansion

Reynolds, W. N.

Striepens, A. H.

English

NASA Technical Reports Server

August 1973	 B73-10254 
•	 .
 
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Lyndon B. Johnson Space Center 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Graphite/Polyimide Laminates with Near-Zero Thermal Expansion 
3 Plies 00 to Long Axis 
+450 to Axis 
.45° to Axis 
2 Plies 900 to Axis 
450 to Axis 
+450 to Axis 
3 Plies 00 to Axis 
.,
	
jOrzO	 12 Plies Identical to Those Shown 
for Upper Half of Specimen 
Figure 1. Graphite/Polyimide Shaft Layup 
[IJ
Composite structures of graphite and polyimides can 
be laminated to have very low coefficients of thermal 
expansion. Such structures are light and strong and have 
Rounded End for
	
Graphite/Polyimide 
Shaft Extension Threading into 
Shaft of Dial 
Gauge / Insulated 
Specimen / Hot Chamber 
est
Dial	 I	 Heat 
Deflection 
Indicator 
Figure 2. Dilatometer with Graphite/Polyimide Extension
many uses where expansion or contraction with temper-
ature change is undesirable. One application is with 
instruments that measure thermal expansion. 
The low thermal expansion is achieved through a 
special layup of the laminates. The unidirectional fiber-
reinforced layers are oriented at angles with one another 
as shown in Figure 1. Depending on the materials used, 
coefficients of expansion for this Iayup are on the order 
of iO over temperature ranges of 75 to 3000 F (25 
to 150° Q. 
These composites provide an order of magnitude 
improvement over quartz dilatometer systems (coef-
ficient of thermal expansion about 10- 6 ) normally used 
to measure thermal expansion. A dilatometer has been 
designed (see Figure 2) that, uses 1/8 x 1/8 x 2 in. 
(0.3 x 0.3 x 5 cm) strips of the composite as extensions 
between the dial indicator and the test specimen. The 
extensions are threaded into the shaft of the deflection 
indicators and eliminate thermal expansion in the de-
flection measuring system.
(continued overleaf) 
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Technology Utilization Officer 
Lyndon B. Johnson Space Center 
Code JM7 
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Reference: TSP73-10254
Patent status: 
NASA has decided not to apply for a patent. 
Source: W. N. Reynolds and
A. H. Striepens of
Rockwell International Corp. 
under contract to
Johnson Space Center
(MSC-17662, 17928)
1 0 
. 
B73 . 10254	 Category 04, 06


Graphite/polyimide laminates with near-zero thermal expansion

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