Program involves development of process technique for boron-polyimide prepeg, lay-up and curing procedures for prepegs when processed under vacuum bag pressure, and development and evaluation of titanium hard points for smooth transition of loads from titanium attach points into boron reinforced body of structure

Clark, G. A.

English

NASA Technical Reports Server

July 1972
	 B72-10353 
o NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Titanium Reinforced Boron Polyimide Composite 
High modulus reinforced composites are being in-
creasingly used due to their higher strength-to-weight 
and stiffness-to-weight ratios. The application of opti-
mized, oriented, filamentary composite structures in 
aerospace applications has been limited by low stiffness, 
bearing characteristics and, in some instances, temper-
ature deterioration. The low stiffness (composite modu-
lus) has been overcome by the development of boron 
and high modulus graphitic filaments. The elevated 
temperature characteristics have been improved by such 
polymers as polyimides, polybenzimidazoles, polyben-
zothiazoles, etc. These resin systems have not, however, 
beencompletely characterized for their processing charac-
teristics, particularly as they apply to production type 
tooling. Bearing characteristics and concentrated load 
transfer through hard points still remain problem areas 
where minimum weight is required. 
One good approach to reducing the weight of hard 
points is to incorporate lightweight metal shims to aug-
ment the strength of the composite. To minimize strains 
at the metal-composite interface, the component must 
have compatible linear coefficients of thermal expansion. 
A boron composite with any resin system is reasonably 
compatible with stainless steels, but more compatible 
with titanium sheet materials. Graphite composites im-
pose problems in the incorporation of metal shims since 
they have a slightly negative coefficient of expansion in 
the longitudinal direction. 
The intended use of any material imposes considera-
tions on how it will be processed. One application of 
interest considered in the development effort, but not 
to be done under this program, was the fabrication of a 
conical section 9.75 meters (32 ft) in diameter at the 
base, tapering to 8.65 meters (28 ft) in approximately
2 meters (6 ft). The size of such a section obviously pre-
cludes the press molding of the component in one piece. 
It also severely limits the facilities for autoclave or hydro-
dave molding. Thus, the processing technique established 
for concentrated effort was conventional vacuum bag 
molding. 
This program involved the development of the process 
technique for boron-polyimide prepreg, the lay-up and 
curing procedures for the prepregs when processed under 
vacuum bag pressure, and the development and evaluation 
of titanium hard points for the smooth transition of 
loads from the titanium attach points into the boron 
reinforced body of the structure. This information, after 
data generation, was applied to the modification of a box 
beam design which had previously been fabricated of 
boron-epoxy. After verification of the design, the com-
ponent was fabricated and structurally tested at the 
maximum temperature capability of the system. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812 
Reference: B72-10353 
Patent status: 
No patent action is contemplated by NASA. 
Source: G. A. Clark of
North American Rockwell
under contract to
Marshall Space Flight Center

(MFS-21916) 
Category 04 
This documentwas prepared underthe sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000352 2020-03-17T03:30:05+00:00Z


Titanium reinforced boron polyimide composite

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