A deployable M-braced truss structure, efficiently packaged into a compact stowed position and expandable to an operative position at the use site is described. The M-braced configuration effectively separates tension compression and shear in the structure and permits efficient structural design. Both diagonals and longerons telescope from an M-braced base unit and deploy either pneumatically, mechanically by springs or cables, or by powered reciprocating mechanisms. Upon full deployment, the diagonals and longerons lock into place with a simple latch mechanism

Mikulas, M. M., Jr.

Rhodes, M. D.

English

NASA Technical Reports Server

United States Patent p i ]  Patent Number: 4,604,844 
Mikulas, Jr. et al. [45] Date of Patent: ,Aug. 12, 1986 
[54] DEPLOYABLE M-BRACED TRUSS 
STRUCTURE 
[75] Inventors: 
[73] Assignee: 
[21] Appl. NO.: 
[22] Filed: 
Martin M. Mikulas, Jr., 
Williamsburg; Marvin D. Rhodes, 
Yorktown, both of Va. 
The United States of America as 
represented by the Administrator of- 
the National Aeronautics and Space 
Administration, Washington, D.C. 
760,378 
Jul. 30,1985 
r511 Int. Cl.4 ...................... E04H 12/18: E04G 25/04 
L- -.I ~ ~ 
[52] US. Cl. ........................................ 52/632; 52/111; 
52/645: 52/646 
[58] Field of Search ................. 52/632, ill, 118,-645, 
52/646 
r561 References Cited 
U.S. PATENT DOCUMENTS 
253,520 2/1882 Du Bois ............................ 52/645 X 
1,073,925 9/1913 Pichler .................................. 52/632 
2,176,965 10/1939 Haynes ............................. 52/646 X 
3,213,575 10/1985 Boczek . 
3,693,309 9/1972 Kutchai ................................. 52/632 
1,802,373 4/1931 Byers ................................ 52/632 X 
3,830,031 8/1974 Solsson . 
3,885,648 5/1985 Beziat . 
3,835,612 9/1974 Beziat ............................... 52/646 X 
4,089,147 5/1985 Bain 
FOREIGN PATENT DOCUMENTS 
108001 6/1958 Pakistan ................................ 52/646 
643615 1/1979 U.S.S.R. ................................ 52/111 
Primary Examiner-Alfred C. Perham 
Attorney, Agent, or Firm-Howard J. Osborn; Wallace 
J. Nelson; John R. Manning 
[571 ABSTRACT 
The disclosure relates to a deployable M-braced truss 
structure that is efficiently packaged into a compact 
stowed position and expandable to an operative position 
at the use site. The M-braced configuration effectively 
separates tension-compression and shear in the structure 
and permits efficient structural design. Both diagonals 
and longerons telescope from an M-braced base unit. 
They are deployed either pneumatically, mechanically 
by springs or cables, or by powered reciprocating 
mechanisms. Upon full deployment, the diagonals and 
longerons lock into place with a simple latch mecha- 
nism. 
5 Claims, 3 Drawing Figures 
34 
https://ntrs.nasa.gov/search.jsp?R=19860023265 2020-03-23T07:18:28+00:00Z
U.S. Patent Aug. 12,1986 Sheet 1 of 3 4,604,844 
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FIG. 1 
U.S. Patent Aug. 12,1986 Sheet 2 of 3 4,604,844 
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FIG. 2 
U.S. Patent Aug. 12,1986 
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FIG. 3 
Sheet 3 of 3 4,604,844 
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Accordingly, it is an object of the present invention 
to provide a novel truss structure that can be compactly 
folded for efficient storage. 
Another object of the present invention is to provide 
5 a structure that allows packaging of very long truss 
structures into a single bay area. 
able truss structure that can be deployed automatically. 
DEPLOYABLE M-BRACED TRUSS STRUCTURE 
ORIGIN O F  THE INVENTION 
The invention described herein was made by employ- 
by Or for the Government for governmental purposes 
ees Of the United States Government and may be used Another object of the present invention is a deploy- 
without the payment of any royalties thereon or there- 
for. 
TECHNICAL FIELD 
The present invention relates to a deployable M- 
braced truss which can be folded for efficient packag- 
ing. 
BACKGROUNDART 
Many space operations of the future will require the 
use of long lightweight deployable booms. These booms 
have application in a number of areas such as a mast to 
support and accurately position the feed-horn for large 
antennas, to deploy and provide tension in the blankets 
of a solar array, or to serve as structural components of 
a space station or operations center. A number of de- 
ployable and/or extendable structural configurations 
have been proposed in the past, most of which are truss- 
type structures composed of load carrying axial mem- 
bers (longerons) stabilized by cross-members (battens) 
and diagonals. The prior art truss configurations have 
either telescoping or folding longerons connected di- 
rectly by diagonals, which are generally constructed of 
cable to facilitate folding and/or packaging. The cable 
must be pretensioned or the structure will have low 
shear stiffness until the deformation is adequate to load 
the diagonal members. However, pretension in the diag- 
onals introduces load in the longerons making them less 
efficient structural members. Column or compression 
loads applied to the longerons will also reduce the ten- 
sion in the wire diagonals. 
Some of these problems can be overcome by using 
diagonals fabricated from members that have bending 
stiffness adequate to support compression loads. How- 
ever, trusses with single diagonals may introduce bend- 
ing or kick loads in the longerons when the truss is 
A further object of the present invention is a deploy- 
10 able truss structure that will form a stiff structural col- 
umn or beam once deployed. 
BRIEF DESCRIPTION OF THE DRAWINGS 
A more complete appreciation of the invention and 
15 many of the attendant advantages thereof will be 
readily apparent as the same becomes better understood 
by reference to the following description when consid- 
ered in connection with the accompanying drawings 
wherein: 
FIG. 1 is a part-schematic view of a compactly folded 
M-braced truss according to the present invention and 
having telescoping diagonals and longerons that tele- 
scope from a base unit; 
FIG. 2 is a view similar to FIG. 1 illustrating the 
25 M-braced truss shown in FIG. 1 in partially deployed 
FIG. 3 illustrates the M-braced truss shown in FIGS. 
20 
condition; and 
1 and 2 when fully deployed. 
DETAILED DESCRIPTION OF THE 
INVENTION 
This present invention has the advantages of a fixed 
M-braced truss while also permitting the structure of 
the truss to be collapsed for compact storage. In an 
35 M-braced truss, the diagonal members intersect at the 
center of a batten rather than at the batten-longeron 
intersection. This structure allows loads introduced in 
the diagonals to be reacted by batten bending. Move- 
ment associated with joint tolerances are eliminated and 
40 ensure the geometric accuracy of the deployable beam 
by using bending of the batten to preload the diagonals. 
Bending the batten limits the contribution or interaction 
of load in the diagonal due to applied axial load. How- 
ever, the diagonals are effective in reacting shear loads 
30 
45 because the triangular pattern cannot be distorted with- 
out introducing loads in the diagonal members. There- 
fore, the M-braced configuration effectively separates 
loaded in compression. Trusses with cross-diagonals, 
while eliminating this moblem, are more difficult to 
fold and the diagonals must be adequate to support not 
only loads introduced by shear, but structural redun- 
dancy causes part of the axial load to be introduced in 
the diagonals. Trusses with folding members also re- 
quire the lengths of all members to be precisely set and 
the stiffness of the deployed structure is significantly 
affected by tolerance in the joints. 
STATEMENT OF THE INVENTION 
The present invention, is directed toward an effi- 
ciently packaged deployable M-braced truss, and elimi- 
nates or minimizes the problems of prior art systems. In 
an M-braced truss, the diagonals intersect at the center 
of the batten which is more structurally efficient than 
the traditional truss where diagonals intersect at the 
batten-longeron intersection. The present invention 
compactly folds and the diagonals and longerons tele- 
scope from a base element. Deployment of the M- 
braced truss can be performed manually, pneumatically, 
mechanically, by springs or cables, or by a powered 
reciprocating mechanism in a conventional manner. 
- -  
tension-compression and ;hear in the structure and per- 
mits an efficient structural design. 
An important aspect of the present invention is that 
the diagonals and longerons telescope from a base ele- 
ment, permitting several sections of the truss to be pack- 
aged into a single bay section for launch. Referring now 
more particularly to FIG. 1, the truss structure of the 
55 present invention is shown compactly folded and desig- 
nated generally by reference numeral 10. In the illus- 
trated embodiment the base or first unit 11 of truss 10 
includes diagonals 16,18, longerons 20,22 and battens 
24,26. 
The partially deployed truss 10 as shown in FIG. 2 
more clearly illustrates diagonals 12,13, longerons 28,29 
and batten 32 which, along with batten 26 of unit 11, 
constitutes the second or intermediate unit of truss 10. 
Longeron 32 also connects with diagonals 14,15, and 
65 longerons 30,31 which, together with batten 34, forms 
the third or end unit of the illustrated truss structure 10. 
Diagonals 16,18 of the base unit are fixed in the ex- 
tended position shown while diagonals 12,13,14 and 15 
50 
60 
3 
4,604,844 
in the preferred embodiment are formed of three tele- 
scoping segments. Also, the converging ends of diago- 
nals 16,18 are fixed to batten 24 via bracket 38 while the 
converging ends of diagonals 12,13 and 14,15 are pivot- 
ally connected to respective battens 26 and 32. Simi- 
larly, the extended ends of diagonals 16,18 are rigidly 
secured to the respective intersections of longerons 
2 0 3  with batten 26. 
Diagonals 12,13 are pivotally connected via pivot 
pins 40,41, respectively, at their converging ends to a 
bracket 42 fixed intermediate to batten 26. The extended 
ends of diagonals 12J3 are pivotally connected via 
respective pivot pins 44,46 to brackets or ears 45,47 
which, in turn, are rigidly secured at the inside area of 
the rigid corner connection elements 49,51 of longerons 
28,29 with batten 32. Corner connection elements 4931 
are formed of two tubular sections welded or otherwise 
rigidly attached to form a right angle that serves to 
receive and attach to, respectively, longeron 30, batten 
32 and longeron 28; and longeron 31, batten 32 and 
longeron 29. Similar corner connection elements are 
provided at each end of battens 24,26 and 34 but are not 
elaborated on in the interest of clarity. The vertical leg 
of corner connection elements 49,51 are provided with 
transverse openings therein for receiving spring urged 
latch pins 53,54, respectively, to lock or latch longerons 
30,31 in the extended position shown in FIG. 3. The 
other corner connection elements (not designated) on 
bottom unit 11 are also provided with similar openings 
for receiving the spring urged latch pins carried by 
longerons 28,29. Latch pins 53,54 and those not desig- 
nated are of similar construction to the conventional 
latch pins employed on telescoping tent poles. 
QPERATION 
The operation of the invention is now believed appar- 
ent. When the compactly folded M-braced structure is 
stowed or retracted, it is as shown in FIG. 1. As longe- 
rons 28,29 and 30,31 are deployed, the M-braced diago- 
nals P2,13,14,15 are telescopically expanded and formed 
as the battens 32,34 are moved away from base unit 11 
as shown in progress in FIG. 2. Upon full deployment, 
the longerons %8,29,30,31 are locked in place by latch 
pins 53,54 and the diagonals 12,13,14,15 are also locked 
by similar spring urged pins, not designated, to result in 
three basic M-braced truss segments as shown in FIG. 3. 
Although the invention has been described relative to 
a three-unit embodiment9 the number of units is a design 
choice and any multiple of units needed fool a specific 
final configuration may be employed and are considered 
within Ehe scope of the present invention. 
Deployment of the M-braced truss can be performed 
manually pneumatically, mechanically by springs or 
cables, or by a powered reciprocating mechanism. 
Component members for the M-braced truss may be 
fabricated from conventional metallic materials or non- 
metallic materials such as graphite-epoxy. 
Further, although the diagonals 12,13,14,15 are 
formed ~f three telescoping sections, it is to be under- 
stood that this number may be varied as the design 
dictates. The preferred embodiment utilizes the base 
segment for each diagonal as a one-half length of the 
adjacent batten to facilitate compact stowage. Although 
longerons 20,28,30 and 22,29,3B are by necessity of 
decreasing size due to the telescope stowage thereof, 
the individual diagonals for the extended units remain of 
the same size since each diagonal unit is separately 
stowed. 
5 
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Although the invention has been described relative to 
a specific embodiment thereof, it is not so limited and 
numerous variations and modifications thereof will be 
readily apparent to those skilled in the art in the light of 
the above teaching. For example, although the specific 
embodiment selected for illustrating the present inven- 
tion utilizes only two longerons in each segment it is to 
be understood that the invention is equally applicable to 
triangular, square or other multi-side truss segments and 
the beam segments of such structures would employ 
three, four, or more longerons in each beam or column 
segment. It is therefore to be understood that within the 
scope of the appended claims the invention may be 
practiced otherwise than as specifically described. 
What is claimed as new and desired to be secured by 
Letters Patent of the United States is: 
1. An expandable truss structure formed of multiple 
interconnected truss units, 
each said truss unit including at least one elongated 
structural batten, at least one longeron attached to 
each end of said batten and a pair of diagonal struc- 
tural members connected at one end thereof to 
substantially the intermediate length of said elon- 
gated structural batten and connected at the other 
end thereof adjacent to the end of one said longe- 
ron, wherein said multiple interconnected truss 
units comprise a base unit, at least one intermediate 
unit and an end unit, said base unit having rigidly 
connected longerons and diagonals attached to said 
elongated structural batten and said at least one 
intermediate unit and said end unit each having 
parts thereof folded and parts thereof telescopi- 
cally received by said base unit to form a compact 
structure adapted to be moved from the compact 
stowed position to an expanded operative truss 
structure, and wherein the diagonal structural 
members of said at least one intermediate unit and 
said end unit are hingedly connected at one end 
thereof to said elongated batten of the respective 
unit substantially at the intermediate length 
thereoE 
2. The truss structure of claim 1 including each said 
diagonal structural member of said at least one inteme- 
diate unit and said end unit being formed of telescoping 
segments and wherein the end segment of each diagonal 
hingedly connected to said elongated batten is substan- 
tially equal to a one-half length of said elongated batten 
and is adapted to telescopically receive the remaining 
segments of said diagonal when the truss structure is in 
the compactly stowed mode. 
3. The truss structure of claim 1 including a corner 
connector element serving to secure the end of each 
said elongated batten to one end of said at least one 
longeron, said corner connector being formed of right 
angle disposed tubular segments, and wherein there are 
three interconnected truss units disposed in a compact 
stowed configuration and comprising a base unit, one 
intermediate unit and an end unit, and 
including latch means for locking the truss structure 
when expanded or deployed from the compact 
stowed configuration to an extended use configura- 
tion, said latch means including latching parts dis- 
posed on said corner connector elements and on an 
end of said longerons. 
4. An M-braced truss structure comprising: 
a plurality of interconnected truss sections, 
each said truss section having at least one elongated 
structural cross-member or batten, 
4,604,844 
5 6 
at least one axial structural member or longeron at- 
tached to each end of said batten, 
a pair of diagonal structural members hingedly con- 
nected at one end thereof substantially intermedi- 
end thereof to an end of one said longeron, and 
each said longeron and each said diagonal being 
moved from a stowed compressed position to an 
expanded operative truss structure. 
for 
operative position when deployed to form a stiff struc- 
tural column or beam. 
s. The truss of claim including latch 
ate said batten and hingedly connected at the other 5 latching the plurality of truss section in the expanded 
formed of telescoping segments and adapted to be * * * * *  
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Deployable M-braced truss structure

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