IRJET- Development & Analysis of a Prototype Dismountable Tensegrity Structure

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 3890
Development & Analysis of a Prototype Dismountable Tensegrity
Structure
1Sameer Pinjari, 2Md Amir Sohel, 3Ejaj Ahmed, 4Karim sk, 5Golam Mortuja & 6Sayed Haamid Ali.
1Professor & 2,3,4,5&6Final Year Civil Engineering Student
Jamia Institute of Engineering & Management Studies, Akkalkuwa, North Maharashtra University
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Abstract-The tensegrity structure isalowweightstructure
which is constructed by tension and compression member.
Then characteristics advantages and disadvantages of these
structures are discussed in detail, followed by a review of little
simple tensegrity structure. This paper presents a new
technique for development of tensegrity structure and their
deployment in field, in two different modes-struts based and
cable based.
Key Words: Tensegrity, Light-Weight, Analysis,Deployable,
Controllable, Energy-Efficient, Dismountable.
1. INTRODUCTION
The word tensegrity comes from the construction of tension
and integrity. a tensegrity structure consists of a set
discontinuous compression members tied together by
continuous tensile member, generally cables. Tensegrity
structure essentially consist of bars and strings which are
attached to the end of the bars. the bars are always in
compression whereas the strings are alwaysintension.They
are lightweight, adaptable, deployable, and space efficient
structure in which the struts appear to be floating in the air.
The basic property of tensegrity structure is that they
acquire their rigidity by the application of tension on cables.
From engineering point of view, itisalsodefinedasstatically
indeterminate reticulatedsystem.Thistypeofstructureuses
many interesting structure property, because their
composition, they are relativity light weight.
Figure 1: Prototype Tensegrity Structure
1.1 Definition
TENSEGRIY = TENSION + INTEGRITY
TENSEGRIY, tensionalintegrityorfloating compressionis
a structural principle based on the use of isolated
components in compression inside a net of continuous
tension, in such a way that the compressed members
(usually bars or struts) do not touch each other and the pre
stressed tension members (usually cables or tendons)
delineate the system spatially.
1.2 Concept of Tensegrity Design
Tensegrity structures are structures based on the
combination of a few simple design patterns:
 Loading members only in purecompressionorpure
tension, meaning the structure will only fail if the
cables yield or rods buckle.
 Preload or tensional pre-stressed which allows
cables to be rigid tension.
 Mechanical stability, which allows the member to
members to remain in tension/compression as
stress on the structure increase.
Because of the patterns, no structural member experiencesa
bending moment. This can produce exceptionally rigid
structures for their mass for the cross section of the
components.
2. BENEFIT OF TENSEGRITY STRUCTURE
a) Tension stabilizes the Structure.
b) Tension structures are Efficient.
c) Tensegrity structures are Deployable.
d) Tensegrity structure are easily Tunable.
e) Tensegrity structures can more Reliable Modelled.
f) Tensegrity structurecanperformMultipleFunction.
3. MATERIAL CHARACTERIZATION
Tensegrity structures generally consist of soft members
(cables) and hard members (struts). It is essential to

determine the material properties i.e. the Young’s modulus
(E), yield strength and the ultimate strength of both the
tension and the compression members before they can be
employed for fabrication. In this study Indian Standards IS
1239-I (1990), were used as compression members. The
market confirming to IS 3459 (1977), were used as tensile
members. The GI pipes
Table -1: Properties of GI pipe as per IS 1239
PARAMETER VALUE
Nominal bore diameter 15 mm
Thickness 2.6 mm
Mass 1.21 kg/m
Maximum outside diameter 21.8 mm
Minimum outside diameter 21
Tolerance in thickness -10% to + unlimited
Minimum tensile strength 320 N/mm^2
Table -2: Properties of Stander Wire as per IS 3459
PARAMETER VALUE
Nominal diameter 4mm
Construction 6*19(12/6/1)
Approximate mass Round
Minimum breaking load 6.09 kg/100
Tolerance in thickness
9.4 KN for 1770 grade steel
10.4 KN for 1960 grade steel
Tolerance in thickness + 6% to -1%
were tested in the universal testing machine (UTM) of 100t
capacity. Four strain gauges of 5mm gauge length,
manufactured by Tokyo Sokki Kenkyujo Company Limited
(TML, 2005), were surface bonded in the middle portion
along the circumference of the GI pipe using Cyanoacrylate
(CN) adhesive. The strain gauges were connected to the data
logger card fixed on a personal computer for automatically
recording the strains using strain smart datasystem, version
3.1. The average strain was considered for determining
Young’s modulus of the pipe. The internal and external
diameters of four pipesweremeasuredandtheaverageinner
and outer diameter was
Figure 2: Eye bolt
Figure3: Eye bolt joint with GI pipe
Figure 4: Stranded weir
found as 15.9 and 21.375 mm respectively and the cross
sectional area was calculated as 160.284mm2. Three pipes
were tested and the stress strain curve. The averagevalueof
Young’s modulus was computed as 2.05× 105 N/mm2. The
average breaking load was 65727 N and the corresponding
ultimate stress was 410 N/mm2. Hence, the GI pipes
confirms to 240 grade as per IS 1161 (1998) and the yield
stress is 240 N/mm2.

Figure 5: Different Stages of Deployment of Tensegrity
Structure in Cable Mode,
(a) Stage 1, (b) Stage 2, (c) Stage 3
4. OBJECTTIVE
The qualities of tensegrity structure, which make the
technology attractive for human use, are their resilience and
ability to use materials in a very economical way. Thedesign
of tensegrity structure is complex and iterative process.
Hence this research mainly focused on development of
dismountable tensegrity structure, themainobjectiveofthis
research can be summarized.
1. To develop a dismountable single tensegrity structure
module (1m x 1m) based on half cuboctahedron
configuration.
2. To extend it to a 2m x 2m dismountable tensegrity
structure grid (by joining four single modules) on half-
cuboctahedron configuration for shelter purpose.
3. Development of new design approach using artificial
neural network(ANN).
5. METHODOLOGY ADOPTED
The design of tensegrities is divided into three distinct steps
1. From-finding tensegrity
2. Structural stability tensegrity
3. Load analysis tensegrity
Form-Finding is an essential problem in the design of
tensegrity systems, since the Fulfillment of stability
requirements depends on both the shape and geometry.The
solution requires simultaneously solving the geometry and
self-stress. Thus, any form finding method would be either
based on geometry or mechanics, but both aspects still need
to be taken into account that two main methods are
available, namely form-controlled and force controlled. The
first aspect of the form-finding problem is determining the
arrangement and connectivity of the system, such that it is
capable of structural stability.
6. ADVANTAGES AND DISADVANTAGES
6.1 Advantages
• Due to the ability of the structure to respondasa whole,
it is possible to use materials in a very economical way,
offering maximum amountofstrengthfora givenamount
of building material. The construction of towers, bridges,
domestic. employing tensegrity principles will make
them highly resilient and, at the same time, very
economical.
• Tensile forces naturally transmit themselves over the
shortest distance between two points; hence the
members are precisely positioned to best withstand
stress.
• The fact that these structures vibrate readily means
that they transfer loads very quickly, so the loads cannot
stress the structure locally. This is very useful in termsof
absorption of shocks and seismic vibrations.
• The spatial definition of individual tensegrity modules,
which are stable by themselves, permits an exceptional
capacity to create systems by joining them together.This
conception implies the option of the endless extensionof
the assembled piece.
• For large tensegrity constructions, the fabrication
process would be relatively simple to carry out, sincethe
structure is self-scaffolding.
6.2 Disadvantages
• Tensegrity arrangements sometimes face the problem of
bar congestion.
• Several experts do not prefer tensegrity structures due to
large deflections
• The fabrication complexity is also a barrier for developing
the floating

Compression structures. Spherical and domical structures
are complex, which leads to problems in production.
• The absence of adequate commercial design tools has also
been a limitation until now. There was a lack of design and
analysis techniques for these structures.
7. APPLICATIONS
Tensegrity structures are attractive solutions under
following circumstances:
I. Portable and foldable structures: such as for
disaster struck areas, nomadic communities and
field hospitals.
II. Superstructures for embedded substructures in
order to escape terrestrial confines (e.g. in
congested or dangerous urban areas,floodplainsor
irregular, delicate or rugged terrains).
III. Tensegrity Towers can be used as Lightning
conductors. Insituationswherelargedisplacements
are not a matter of concern or considerable
displacements areacceptable,tensegritytowerscan
be employed to support antennas, receptors, radio
transmitters, mobile telephone transmitters, etc.
IV. Refugee or hiking shelters.
V. Foldable reflector antennas and masts for large
retractable appendages in spacecraft.
VI. Frames over large areas for environmental control,
energy transformation and food production
VII. Tensegrity systems can beusedtomake economical
furniture like chairs, tables, lamps etc.
VIII. Exclusion or containment of flying animals or other
objects.
8. CONCLUSION
Tensegrity structures in real life can be monitored online
using wireless technology and the damage can be detected
by comparing the frequencies in intervals. It is observed the
damage in both cables and struts can bedetectedbybonding
a single PZT patch on a strut member. The frequencies
undergo greater change for damage in the strut than the
cable. Low frequency technique is suitable for detecting
global damage in the single module as well as grid structure
where as high frequency technique (EMI technique) is able
to detect localized damage i.e. on individual member.Hence,
it is possible to detect damage in the tensegrity structure in
field by bonding a single piezo sensor. A single piezo sensor
bonded to a strut also provides information regarding
damage occurrence with respect to nodes of the tensegrity
structure. Further theoretical and experimental studies are
required for locating damaged elements of tensegrity
structures.
This thesis reviews the definitions, different form finding
methods, static and dynamic analysis, design and
deployment of tensegrity structures in detail. Further, the
main properties, advantages, disadvantages and potential
applications of tensegrity structures have been highlighted.
The research mainly highlights on fabrication and testing of
dismountable tensegrity single module and tensegrity grid
structure based on half cuboctahedron configuration.
Numerical models of the structures have been validated
experimentally. The dismountable tensegrity grid is easy to
fabricate and assemble/dismantle and does not require
lifting machine and equipment’s.Further, noskilledlabouris
required for restressing. Hence, the proposed structural
system is ideal for field deployment. The structure requires
less space for storage and is easy totransport. Thetensegrity
grids reported so far in the literature require mechanization
in field application, which is likely to bring up the overall
operational cost. In addition, the proposed method reduces
the number of cables. Artificial neural network is employed
as an alternate design approach for the proposed structural
system. To the best knowledge of the researcher, this is the
first time such a structure has been comprehensively
monitored using conventional as well as smart sensors.
9. REFERENCE
I. Adriaenssens S M L and Barnes M R 2001
Tensegrity spline beam and grid shell structures
Engineering Structures 23 29-36, ANSYS version 9
2004.
II. Argyris J H, Scharpf DW 1972 Large deflection
analysis of prestressed networks Journal of the
Structural Division ASCE 98 633-54.
III. Barnes M R 1977 Form finding and analysis of
tension space structures bydynamicrelaxationPhD
thesis The City University of London.
IV. Barnes M R 1994 Form and stress engineering of
tension structure Structural Engineering Review 6
175-201.

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