for deployable antennas - nasa deployable antennas r. mi. bluck and r. r. johnson lockheed missiles...
TRANSCRIPT
NASA Contractor Report 172164
FABRICATION OF SLENDER STRUTS
NASA-CR-172164 19830023462
FOR DEPLOYABLE ANTENNAS
R. MI. BLUCK AND R. R. JOHNSON
LOCKHEED MISSILES & SPACE COMPANY} INC. SUNNYVALE} CALIFORNIA 94086
TASK ASSIGNMENT NO. 24 CONTRACT NAS 1-14887
APRI L 1983
NI\S/\ National Aeronautics and Space Administration
langley Research Center Hampton, Virginia 23665
111111111111111111111111111111111111111111111 NF02523
.... , (') ,"," ,j(lf'jn .' II·, ", I .,
I', ~! • • I
U\NGL;:Y RFS::AFIr;H UNTFk Li8iiP,RY, NASA
Ht.r\'l?TON, VlftGINIJI.
https://ntrs.nasa.gov/search.jsp?R=19830023462 2018-07-10T21:09:13+00:00Z
NASA Contractor Report 172164
FABRICATION OF SLENDER STRUTS FOR DEPLOYABLE ANTENNAS
R. Nt BLUCK AND R. R. JOHNSON
, LOCKHEED MI SS I LES & SPACE COMPANY} I NC I
SUNNYVALE} CALIFORNIA 94086
TASK ASSIGNMENT NO. 24 CONTRACT NAS 1-14887
APRI L 1983
NI\5/\ National Aeronautics and Space Administration
Langley Research Center Hampton, Virginia 23665
NB3-3J73~
CONTENTS
ILLUSTRATIONS v
TABLES vii
INTRODUCTION 1
DESCRIPTION OF STRUTS 1
PROCESS RATIONALE 2
MANUFACTURING PROCESS 8
VERIFICATION REQUIREMENTS 1.1
iii
1
ILLUSTRATIONS
Graphite Epoxy Struts, Aluminum Foil Skin
Gl'aphite Fiber: T-300
2 Graphite Epoxy Struts, Aluminum Foil Skin
Graphite Fiber: 55 MSI Pitch
3 Graphite Epoxy Struts, Aluminum Foil Sldn
Graphite Fiber: 75 MSI Pitch
4 Graphite Epoxy struts, Aluminum Foil Skin
Graphite Fiber: 100 MSI Pj.tch
5 Overall Winding Setup
6 Closeup From Top
7 Looking Upward
8 Fabl'icated Tubes
v
4
5
6
7
10
10
10
10
INTRODUCTION
Large diameter aperture antennas have been identified by government and
industry studies as a requirement for radiometer and communication missions for
the 1990 time frame.
The inherent stiffness associated with tetrahedral truss structures makes
them particularly well suited for this application. The work described in this
report deals with the manufacturing development of slender struts required for
the efficient stowage of such deployable trusses in the Orbiter cargo bay. A
number of features are included in both design and the manufacturing process.
The strut design includes an overwrap of aluminum foil which significantly
improves the thermal conductivity, and has the potential to act as a vapor bar
rier if necessary, and provides a thermal control surface.
A number of elements have been introduced into the manufacturing process
which reduces the labor intensive aspects of fabricating these elements.
Included among these elements is the use of a vertical winding machine, teflon
mandrl31, dry fiber placement, aluminum foil winding off of canted spools, and a
pre-wound creeled fiber array.
DESCRIPTION OF STRUTS
Long slender tubular struts approximately 5-m long and 12.7-mm in diam have
been identified by the NASA Langley Research Center as the elements required
for efficient stowage and deployment of large truss supported antennas.
Although strut requirements have not been fully defined at this time, they must
be stiff and thermally stable. One concept for achieving these properties is
the us-e of high modulus graphite epoxy, oriented in the longitudinal direction,
overwrapped with thin aluminum foil. Use of the foil provides the potential
for significant improvements over conventional graphite epoxy struts. The more
important of these features are an improvement in thermal conductivity and the
incorporation of a vapor barrier. Thermal gradients, which are a result of
nonuniform heating will be reduced as the conductivity is increased. The use
of an aluminum surface has been shown to almost completely control the absorp
tion (or desorption) of moisture, if it is a problem.
1
Estimated properties have been determined for four types of longitudinal
fiber/epoxy, overwrapped with aluminum foil. These properties are based on the
data shown in Table 1, for a 60-percent fiber volume, and are presented in
Figs. 1 through 4. The four types of graphite fiber are T-300, VSB-32(55
MSI), VSC-32(75 MSI), and VS-0054(lOO MSI). The effect of a thin aluminum
layer is readily evident. For example, the addition of a layer of 1 mil of
aluminum on the surface of an 0.020-in. wall of P-75 (Fig. 3) GR/E results in
a transverse thermal conductivity of approximately 3 Btu/hr-ft-OF, compared
with 0.1 for bare GR/E. This is accomplished with almost no reduction in
modulus of elasticity (43 versus 44 MSI). In this case, the coefficient of
thermal expansion (CTE) is negative (-0.5 /oF). A zero CTE can be obtained
using 100 MSI pitch fiber and 3.5 mils of aluminum, curve 3, Fig. 4. For this
example, E is 47 MSI and K = 32 Btu/hr-ft-oF. The density of such a structure
is 0.075 Ib/in. 3
For cases where a slightly negative CTE is desired to compensate for
positive CTE joints and fittings, it is possible to obtain higher values of E,
and lighter weight structures.
Point (A), Fig. 4 represents a modulus of elasticity to density (E/p) value
of approximately 109in • Although this point is for a bare (no aluminum)
graphite epoxy tube, it should be easy to achieve the 109 -in. value. A
65-percent fiber volume or a higher modulus fiber would make it possible to
obtain this value with the aluminum foil wrap.
PROCESS RATIONALE
The struts were wound on the LMSC vertical winding machine using dry
fiber. Two methods of introducing the resin were considered. One procedure
incorporated a doctor blade for spreading the resin during the winding
procedure as the carriage traverses from the bot tom of the machine to the
top. This procedure was used for manufacturing the parts which were wound
with aluminum foil. A second approach was to use resin injection for the
graphite
developed
parts without
during this
the aluminum foil wrap.
study. A brief discussion
This
of
procedure was
the rationale
not
for
selecting the mandrel, the vertical winding machine, and the fiber handling
system is presented below. 2
Table 1
ESTIMATED PROPERTIES
GR/E = 60-Pe.rcent Fiber Volume
T-300 P-55
EL - MSI 20 34
ET - MSI 1.5 0.9
0.29 0.3
GLT - MSI 0.66 0.6
CTEL ._ 10-6/ Cl F 0.05 -0.28
CTET ._ 10-6/ Cl F 16.5 19.0
- Ib/in. 3 0.057 0.58
kll - Btu/hr-·ft-OF 3.3 35
k22 - Btu/hr-·ft-oF 0.1 0.1
3
P-75 PI00 Al
44 60 10.5
0.9 0.9 10.5
0.3 0.3 0.33
0.60 0.6 3.97
-0.6 -0.79 13.0
19.0 19.0 13.0
0.063 0.067 0.10
58 137 76
0.1 0.1 76
LI.. 0
I I-LI.. 50 I a::: J: --:::> I-en
40 >-l-
> I-U 30 .t:: :::> 0 Z 0 U ...J 20 « :::2: a::: w J: l-a. 10 0 0 J:
>- 01 ~
LI.. 0 --\u
::t
Z 0 til Z « a. )( w ...J « :::2: a::: w J: I-u. 0 I-Z w -U LI.. LI.. W 0 U ...J « z -0 ::J I-(J Z 0 ...J
I x
II
GRAPHITE EPOXY STRUTS
ALUMINUM FOIL SKIN
GRAPHITE FIBER: T-300
LEGEND
Q) Qj
Q;
tGR/E(in.)
0.020
0.040
0.020
0.040
AL SURFACE ONE SIDE
X ----------
X
~ - - - --- ---- - ---
5.0
4.0
3.0
2.0
1.0
o
til .:2:
>I-
U
li; 16 c:( ...J
w 14 LI.. o til 12 :J ...J :J o 10 o ~
...J c:( Z
o :J I-(J Z o ...J
x UJ
8
6
4
0 ...... o 2345678
tAL - ALUMINUM SURFACE FOIL THICKNESS (MILS)
9 10
-AL SURFACE BOTH SIDES
X
X -- -------
Fig. I Graphite Epoxy Struts, Aluminum Foil Skin-Graphite Fiber: T-300
\J1
60 ..... LL 0 I
l-LL I
a: 50 :I: -::J I-aJ
> 40 I-
> l-U ::J 30 0 Z 0 U ..J « 20 :E a: w :I: I-Il. 0 10 0 :I: I >-~
0
GRAPH ITE EPOXY STRUTS
ALUMINUM FOIL SKIN
LEGEND tGR/E (in.) AL SURFACE AL SURFACE
ONE SIDE 80TH SIDES
r1\ n n"')n v GRAPHiTE FiBER: 55 MSi PITCH I (jD I ~:~:~ X
--LL 0 -w 2.2 ::1. ..... z 2.0 0 I/)
z 1.8 « ll. X w 1.6 ..J « ~ 1.4 a: w :I: 1.2 l-LL 0 1.0 I-Z w 0.8 U LL LL w 0.6 0 U 0.4 ..J « z 0.2 0 ::J I- 0 (j Z o -0 2 ..J •
I x-O.4
lj
36
> 30 I-
U 27 l-I/)
« 211 ..J w LL 21 o I/)
::J 18 ..J ::J
g 15 :E
~ 12 z o 9 ::J I-
(j 6 z 9 I
® 0.020 X
I ® I 0.040 X
/ocx· ® /
/ /
/ /
/ K ® ) -- YR\ ~ - >Ex 0
... '/' <Xx CD , ® I
/ 1// / 1/ //-
Ex CD ' ® K CD, ®
Y
Ex®
// /;?/ 1/ //
/ //. !
/. I /.
I /~ ~ 'I /,y h ,::'l~ 1/7//:;.-"
,,/// v~ 'J~/ " I /,.,.;.4
..... <Xx ® /~K @
,~ Y
x w OL5 ________________________________ __
o 1 2 3 4 5 6 7 ,8 9 10 tAL - ALUMINUI\\ SURFACE FOIL THICKNESS (MILS)
Fig. 2 Graphite Epoxy Struts, Aluminum Foil Skin-Graphite Fiber: 55 MSI Pitch
0-
..... u. 0 I ...
U. I
0::: ::t: --::> f-CC
>-... > ... U ::> 0 z 0 U ..I <: :iE 0::: w ::t: ... w \I)
0::: LIJ > \I)
z <: 0::: ...
>~
60
50
40
30
20
10
o
LEGEND tGR/E(in.) AL SURFACE ONE SIDE
GRAPHITE EPOXY STRUTS ALUMINUM FOIL SKIN
CD @
0.020 X
0.040 X
GRAPHITE FIBER: 75 MSI PITCH ® 0.020
2.0
1.8
1.6
... LL z 0 1.4 w --- '" U ::t
u. -1.2 u. z W 0 o - 1.0 U \I)
..I ~ <: a.. 0.8 Z x i5 W ::> ..I 0.6 ... <: l) :iE Z ffi 0.4 o ::t: ..J ... I u. 0.2 ijXO
o
-0.2
-0.4
-0.6
>- 40 ... U - 36 ... \I)
:5 32 w u. o 28 \I) ::> ..I 24 ::> o o 20 :iE ..I <: 16 z o ::> 12 ... l) z 8 o ..I I x
~--- 0.040 --- --- --_ .. _-------
,'" t3' / x \31
/ /
/ /
/ K Q) ( -=::::::::::=. y .' ,.,E
x @
//~/
I /
/ / / ./
E CD, ® x
Ky CD , ® '" CD, ® x E ® x
! // ./ ,<
/ / ", / /' ./ // ",'" ____ K
y@
/ / ",,-/ -----
I ",/ / ", / / /'" /' -_ ... ", @
/ Y/ -- X
", --0-
;,/ ----./ // ...... -I / ~ ,.,-
'I. ./ --w O~'r~1C __ ~~ ______ ~ ______ ~ __________ ___
o 1 2 3 4 5 6 7 8 9 10 tAL - ALUMINUM SURFACE FOIL THICKNESS (MILS)
AL SURFACE BOTH SIDES
X
X .- -------
Fig. 3 Graphite Epoxy Struts', Aluminum Foil Skin-Graphite Fiber :75 MSI Pitch
-.::J
...... u. o
I
t 60 I
a: ::I: -::> I-a; 50 I
>I-
> 40 I-U ::> o z 8 30 ...J <C ~ a: w ::I: 20 I-w V)
a: w > V)
z <C a: I-
10
>- 0 ~
LEGEND I tG (in.) jAL SURFACEIAL SURFACE R IE ONE SIDE BOTH SIDES
GRAPHiTE EPOXY STRUTS
ALUMINUM FOIL SKIN
CD 2
0.020 x 0.040 X
GR,.t\PH!TE FIBER:
1.6
1.4 1- ...... Z u. 1 2 w 0 • -U w U. ::1. 1.0 u. w z o 0 U - 0.8
V) ...J Z « <C 6 z a. o. o ~ ~ ...J 0.4
<C a ~ Z a: 0.2 o w ...J ::I:
I I- 0 x U.
II 0
-0.2
-0.4
V)
~
>I-
U lV)
<C ...J W
U. o V)
::> ...J ::> o o ~ ...J « z o ::> I-
a z o ...J
I
55
50
45
40
35
30
25
20
15
10
® iOO MSi PITCH ®
0.020
0.040
Ex 0 ccx ® K y ®
Ex CD, ®
/
////~Ky~'@ / /~ --E (j\
;/
x \:V
/ // cc
I / '" x~' @
// ." / / /"''--- -K @
/.(/ ~ y
h/Y //? / // hh
• -" '" __ '" '2'
-0.61 w>- 5 V
/-r
__ x'-"
h . ---,h . ---~ -----
-0.8 o"'~ o 1 2 3 4 5 6 7 8 9 10
tAL - ALUMINUM SURFACE FOIL THICKNESS - MILS
X
X
Fig. 4 Graphite Epoxy Struts, Aluminum Foil Skin-Graphite Fiber: 100 MSI Pitch
A solid teflon rod was used for the mandrel to provide conlpaction, because
of its large coefficient of thermal expansion (CTE) during the cure process.
The teflon rod also provides an easy technique for the removal of the mandrel
from the finished part. The diameter of the teflon rod is reduced by applying
a tension load to the rod, and the part is easily removed.
The LMSC vertical winding machine was used because it provides the most
expeditious means to introduce longitudinal filament, and avoids mandrel sag
during winding. The use of a nonrotating mandrel precludes the potential of
mandrel whip.
A significant reduction in the labor intensive operation of loading the
fiber was achieved by using a Leesona winder to spool the fibers. The fibers
were then mounted on a creel. This procedure made it possible to wind a large
number of parts with only one loading of fiber.
MANUFACTURING PROCESS
The key elements of the manufacturing process include:
o Respool the fiber using the Leesona winder. Up to 1600 ft of single tow
can be wound on one spool.
o Install the 10-ft long 1/2-in diam teflon mandrel.
o Install the spooled fiber on the creel and thread the fiber through the
ceramic eyelets in the fiber alignment plate.
o Install O.OOl-in. thick aluminum foil on the canted stock spools. These
axes are canted to accommodate the aluminum foil overwind.
o Load resin into resin container (Fiber Resin (FR) 8701). During winding,
the resin is fed to a doctor blade for mandrel coating.
8
o The resin, longitudinal fiber, and aluminum foil overwrap are applied in
one pass to the mandrel as the carriage traverses upward.
The wound part is then inserted into a steam-heated, 3-in. diam tubular
oven for curing. After the part is cured, the tube is slipped off the mandrel
by applying mandrel tension, thus reducing the mandrel diameter. The tube is
cured on the mandrel at 250°F for 1 h and then at 335°F for 1 h.
A photograph of the overall setup of the winding operation is shown in
Fig. 5. A capriage is shown on which are mounted the creel of fiber spools, a
plate containing ceramic eyelets through which the fiber is fed, and a
gear-driven rj.ng to which the aluminum foil spools are attached. Also visible
in the picture is the vertically mounted l/2-in. diam mandrel. The length
below the aluminum spools has been wrapped with foil which captures the fiber
as it is wound on the mandrel. Figure 6 is a photograph showing in detail the
fiber being fed through the alignment plate. The spools of aluminum foil, and
the ring to which they are attached, are shown in Fig. 7. Completed tubes are
shown in Fig. 8.
Tubes with other fiber configurations were made using this procedure.
Specifically, a :tlO-deg graphite fiber tube with an aluminum overwrap was
manufactured. In this case, two passes were required. First, the +lO-deg
wrap was put on, and then the -IO-deg wrap and the aluminum foil. A simple
modification is required to the graphite fiber creel mounting. In laying down
unidireetional fiber with the aluminum overwrap, the spools of aluminum foil
are mounted on the rotating ring and the fiber creel is mounted on the
nonrotating frame. For the :tlO-deg configuration, the fiber creel is attached
to the rotating ring which makes it possible to wrap the fiber around the
mandrel"
The aluminum foil used is 1100 full hard (30 ksi UTS), 1/2-in. wide, and
was SelE!cted because it was readily available.
The amount of fiber in each part is precisely known, since a fixed number
of tows (spools) are fed through the ceramic eyelets.
9
L
Fig 6 Closeup From Top
Fig 5 Overall Winding Setup
Fig. 7 Looking Upward fig 8 Fabricated Tubes
10
VERIFICATION REQUIREMENTS
ThE~ objective of this task was to develop a manufacturing process and
demonstrate its feasibility. In this process of making the tubes, a number of
manufanturing elements has been demonstrated.
o AbHity to wind aluminum fiber with good adhesion
o USE! of creeled fiber in the winding process
o Development of a single-pass operation
o Ease of removing mandrel
o Ability to make slender straight tubing
Also, a tube was made with an aluminum foil inside and out by winding the
first foil wrap on the mandrel.
Although the manufacturing feasibility has been demonstrated, more
canplete control of the properties can be achieved by using hard tooling on
the outside, and injecting resin instead of the current technique of spreading
the resin by blade.
More impor'tant, however, is the need for verification of the physical
properties and manufacturing parameters.
In addition to a verification of the properties presented in Figs. I
through 4, a fiber volume and void evaluation are required. The performance
of the foil in the thermal cycling environment of space needs to be
evaluated. The efficiency of the foil as a vapor barrier could be of
considerable importance in some applications. Quantitative data are needed to
evaluate the validity of the manufacturing process.
11
1. Report No. 12. Government Accession No. 3. Recipient's Catalog No.
NASA CR-172164 4. Title and Subtitle 5. Report Date
April 1983 FABRICATION OF SLENDER STRUTS FOR 6. Performing Organization Code DEPLOYABLE ANTENNAS
7. Author(s) R. M. Bluck and R. R. Johnson
8. Performing Or:tnization Report No. LMSC- 889763
9. Performing Organization Name and Address 10. Work Unit No.
Lockheed Missiles & Space Company, Inc. 11. Contract or Grant No. 1111 Lockheed Way NAS 1-14887, Task 24 Sunnyvale, california 94086 13. Type of Report and Period Covered
12. Sponsoring Agency Name and Address Contractor Report
National Aeronautics and Space. Administration Washington, D. C. 20546 14. Sponsoring Agency Code
15. Supplementary Notes
Langley Technical Monitor: Harold G. Bush Final Report
16. Abstract
A procedure for manufacturing long slender graphite tubing is desired. Such tubing has considerable application in truss supported spacecraft applications. The motivation for the selection of the tubing size developed in this program is for use as struts in a NASA, Langley Research Center truss supported antenna concept. The manufacturing procedure uses the LMSC vertical winding machine. A procedure for fabricating graphite epoxy tubing with an aluminum foil inner and outer wrap was also developed. The aluminum foil provides a vapor barrier, significantly improves the thermal conductivity, and provides an excellent thermal control surface.
17. Key Words (Selected by Author(s)) 18. Distribution Statement
Antenna Strut s -Graphite Epoxy Tubing Unclassified - Unlimited Aluminum Foil Surface Manufacturing Subject Category 24
-19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price *
Unclassified Un class ified 17 A02 . .
"For sale by the National Technical Information SerVice, Springfield, Virginia 22161 .