Bi-composite joint serves as interface between two dissimilar materials by interleaving plies of one composite with plies of another. This interleaving forms transition area between composites. Voids are filled in with epoxy resin to form strong, smooth transition between two materials

Dullea, K. C.

Evangelista, J. A.

English

NASA Technical Reports Server

May 1973	 B73-10148 
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. 
A New Concept for Joining Dissimilar Composites 
is	 Graphite/Epoxy	 Boron/Epoxy 
_. Transition 
Bi-Composite
In Bi-Composite Transition 
.
	
Bi-Composite Joint
	 Section 
The problem: 
Various parts of a structure fabricated from compos-
ite materials may have different uses or be subject to 
different stresses. If the structure is made from a com-
bination of different composites, the best composite, 
chosen for its properties and for economy, may be used 
for each part of the structure. However, there has been 
no suitable way of joining unlike composites without 
introducing weaknesses or increasing the weight of the 
structure. 
The solution: 
A new method of joining different laminated com-
posites without mechanical fasteners has been proposed. 
Structures of more than one kind of composite may be 
formed by interleaving the plies of one composite with 
the plies of another. In this way, the properties of each 
composite may be tailored to the requirements of a 
given structure. 
How it's done: 
This bi-composite joint serves as an interface between 
two dissimilar materials. Composites are normally fab-
S
ricated by means, of a tape layup in which plies of the 
materials are stacked in a definite orientation to provide 
the desired mechanical properties. A bi-composite joint 
is made by interleaving the plies of one composite with 
the plies of another. The method is illustrated in the 
figure. 
The interleaving forms a transition area between the 
composites. Voids in this area are filled in with epoxy 
resin to form a strong, smooth transition between the 
two materials. 
There are several advantages to this method: 
1. Lower cost laminates can be used in parts of the 
structure where more expensive composites are not 
necessary. 
2. More flexible fibers can be used where a structure 
has intricate contours. 
3. Properties can be tailored to the structure. For 
instance, a low thermal conductivity composite may 
be used where heat insulation is required, and a high, 
thermal conducting fiber where heat conduction is 
desired. 
4. Virtually any combination of composite materials 
can be joined.
(continued overleaf) 
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Aeronautics and Space Administration. Neither the United Slates 	 information contained in this document, or warrants that such use 
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https://ntrs.nasa.gov/search.jsp?R=19730000148 2020-03-17T07:07:56+00:00Z
Notes: 
No further information is available. Specific questions, 
however, may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B73-10148
Patent-status: 
NASA has decided not to apply for a patent. 
Source: K. C. Dullea and

J. A. Evangelista of

Rockwell International Corp.

under contract to

Marshall Space Flight Center

(MFS-24307) 
B73-10148	 Category 04 S


A new concept for joining dissimilar composites

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