A compliant mechanism is a mechanical device that achieves mobility through the deflection of flexible members rather than traditional movable joints. These mechanisms are utilized in various applications, ranging from everyday products like plastic lids to advanced technologies in biomechanics and aerospace. Compliant mechanisms offer advantages such as reduced part count, enhanced precision, and improved performance due to fewer components and the elimination of lubrication needs.

1. Compliant
Mechanism and
its Applications
Ma chines tha t bend
R A M AIAH
Institute Of Technology
Moha m m ed Ana s B ya ry
1MS 19ME 096

2. What is a
Mechanism?
A m echa nism is a m echa nica l
device used to tra nsfer or tra nsform
m otion, force, or energy. Tra ditiona l
rigid-body m echa nism s consist of
rigid links connected a t m ova ble
joints. Two exa m ples a re shown
below.
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Ramaiah Institute of Technology

3. What is a Compliant
Mechanism?
L.L Howel et.a l [1] - A com plia nt m echa nism is a
m echa nism tha t ga ins a t lea st som e of its
m obility from the deflection of flexible m em bers
ra ther tha n from m ova ble joints only. F or the
com plia nt crim ping m echa nism (a s shown), the
input force is tra nsferred to the output port,
m uch like the vice grips m echa nism , only now
som e energy is stored in the form of stra in
energy in the flexible m em bers.
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Ramaiah Institute of Technology

4. What is a compliant Mechanism?
● In m echa nica l engineering, a com plia nt m echa nism is a flexible m echa nism
tha t a chieves force a nd m otion tra nsm ission through ela stic body deform a tion.
● These m echa nism s a re used to tra nsform m otion, forces or energy from input to
output. As opposed to rigid-body m echa nism s, com plia nt m echa nism s a re
m onolithic a nd ga in a t lea st som e of their m obility from the deflection of flexible
m em bers ra ther tha n m ova ble joints.
● C om plia nt m echa nism s a re a ll a round us, from products we own to high-tech
precision m a nufa cturing equipm ent. Y ou proba bly use m a ny com plia nt
m echa nism s every da y. S om e exa m ples include one-piece pla stic lids (like the
one on ketchup bottles), ta pe m ea sures, ba ttery clips, m ouse buttons, a nd
m a ny sna p-fit pa rts.
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5. A few examples of compliance in
nature
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A few exa m ples of com plia nce in na ture: a spine, bee wings, elepha nt
trunks, bloom ing flowers, a m osquito, sea weed, a nd eels

6. Early compliant mechanism designs include the ancient
bow and many compliant mechanism designs by
Leonardo da Vinci
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7. The Wright brothers used wing warping to achieve control of
their aircraft for sustained human flight
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8. Advantages
P a rt count is reduced by
ha ving flexible pa rts
instea d of springs, hinges
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Precise
Motion
Price
Part
Count
Perfor
mance
Predict
ability

9. Advantages
High precision due to
reduced wea r a nd
reduced or elim ina ted
ba ckla sh.
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Precise
Motion
Price
Part
Count
Perfor
mance
Predict
ability

10. Advantages
Reduced by fewer pa rts
a nd different production
processes
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Precise
Motion
Price
Part
Count Predicta
bility
Perfor
mance

11. Advantages
D evices a re predicta ble
a nd relia ble over a long
period of tim e)
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Precise
Motion
Price Predict
ability
Perfor
mance
Part
Count

12. Advantages
Increa sed perform a nce
due elim ina ting the need
for lubrica tion a t joints
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Price Predicta
bility Perfor
mance
Part
Count
Precise
Motion

13. • D esign C om plexities
• N on-linea r equa tions
• E nergy Retention
• F a tigue Tolera nce
• S trength Lim ita tions
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Disadvantages

14. What are the
fundamental
concepts that help us
understand
compliance?
There are a few straightforward but
counterintuitive concepts that can help
us understand the fundamentals of
compliant mechanisms.
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15. Stiffness and Strength are NOT the
Same Thing
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Usually when we want something to be strong and stiff. For example, the floor in the
upper story of a building we want to be both stiff andstrong. We obviously don’t
want it to break, but we also don’t want it to move around when people walk on it. So
it needs to be stiff and strong.
The rectangular piece of steel
may have the same strength in
different directions, but it will
have very different stiffness for
the two orientations shown

16. It is Possible for Something to be
Flexible AND Strong
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Consider examples of things that are both flexible and strong. Flexible endoscopes
(as shown) are used to examine the interior parts of the body. The endoscope must
be flexible to undergo the required motion and to minimize any trauma from its use
within the body. It must also be strong to withstand the loads that it will undergo
during its use.
A flexible endoscope is an
example of a device that needs
to be both flexible and strong

17. The Basics of Creating Flexibility
The sha pe a nd
siz e of the
m echa nism s
Geometry
How the
m echa nism is
held a nd loa ded.
Loading &
boundary
conditions
N um ber of pa rts
conta ining in the
m echa nism .
Parts
Material
properties
Materials have
different stiffnesses
and Young’s
m odulus
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18. Applications of Compliant Mechanism
Rover wheels,
sola r a rra ys
Aerospace 04
S witches, closure
va lves, circuit
brea kers & cla sps
Electric and
electronics 03
B io inspired com plia nt
wrist, prosthetic finger
Biomechanics
& robotics 02
V a rious ha nd held a nd
m a teria l ha ndling
tools.
Tools 01
Applicatoins
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19. Tools
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L.L Howell et.al [1 ], presented the
methodology for design of
compliant plier as shown in
figure 1 . wherein flexural pivots
are very small in length as
compared to the rigid links.
Biomechanics &
Robotics
Many problems exist with majority of
fingers with conventional rigid links
such as lack of adaptability & this
problem solved by design of a fully
compliant under actuated prosthetic
finger.

20. Electric and
electronics
L.L Howell et.al [1 ], Bistable
mechanism have two stable
position within their motion
range, used as switches, closure
valves, circuit breakers & clasps
Aerospace
BYU-designed solar arrays
inspired by origami
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21. Safing and Arming device for Nuclear
Weapons
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Its purpose is to ensure that no
random vibration say from
earthquake inadvertently disable
safeties and arm the nuclear
weapons. One of the requirements
that this device have to made as
small as possible.
For more info on this device:
https://youtu.be/97t7Xj_iBv0&t=600

22. References
[1 ] Howell L L 2001 Compliant Mechanisms, A John Wiley & Sons, New York
[2] Howell L L, Magleby S P & Olsen B M 201 3 Handbook of Compliant
Mechanism A John Wiley & Sons, Ltd., Publication
[3] S P Jagtap et al 2021 J. Phys.:Applications of compliant mechanism in
today’s world – A review Conf. Ser. 1 969 01 201 3
[4] Howell L L, Midha A 1 994 A Method for Design of Compliant Mechanism
with Small Length Flexural Pivots, Journal of Mechanical Design,
Volume 1 1 6
[5] Brigham Young University Compliant Mechanism research website:
https://www.compliantmechanisms.byu.edu
[6] Veritasium YouTube Channel : Why machines that bend are better
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23. Thank You
R A M AIAH
Institute Of Technology