Transcript Dielectric Elastomers

Dielectric Elastomers
AE 510: Research Project Presentation
By: Carl Johnson
October 22, 2002
How Dielectric Elastomers Work

Dielectric Elastomers have a polymer (aka
plastic) film between two electrodes
 When an electric field is induced between
the electrodes the electrostatic forces cause
a change in shape (see figure)
Ref. 1
Governing Equation of
Dielectric Elastomers
p=e*e0*E2

Where:
– p is effective compressive stress
– e is relative dielectric constant
– e0 is permittivity of free space (a constant)
– E is strength of electric field between diodes
Advantages of Dielectric
Elastomers

Similar materials include:
– Shape memory alloys (SMA)
– Piezoelectrics

Compared to these dielectric elastomers have:
– Higher energy density
– Lower weight
– Higher efficiencies
– Higher maximum strains
Dielectric Elastomer Comparison Chart
Shape Memory
Alloys
Piezoelectrics
Note Similarity of
Dielectric Elastomers
and Natural Muscle
Dielectric
Elastomers
Applications: Actuators




Dielectric elastomers are
well suited to actuators
Their similarity to natural
muscle makes them ideal
for use on robots (see
right)
They could also be used to
motivate insect-like micro
UAVs
Dielectric elastomers
could be used for human
prostheses and make the
six million dollar man a
reality (see title slide)
Applications: Heel-Strike
Generator

DoD is using dielectric elastomers to develop a
heel-strike generator to go in soldiers boots that
would generate electricity just from walking
 A dielectric elastomer generator works like an
actuator in reverse (mechanical-to-electrical
instead of electrical-to-mechanical energy)
References:
1)
Pelrine, Ron et al. “High Strain Actuator Materials Based on Dielectric Elastomers.” SRI
International. 2000.
2)
Wingert, Andrew et al. “Hyper-Redundant Robot Manipulators Actuated by Optimized
Binary Dielectric Elastomers.” Smart Structures and Materials Symposium 2002.
3)
http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-web.htm. SRI International
Comparison Tables/Charts. 2002.
4)
Bar-Cohen, Yoseph. “Electroactive Polymers as Artificial Muscles – Capabilities,
Potentials and Challenges.” Robotics 2000 and Space 2000. Albuquerque, NM. 2000.
5)
Pelrine, Ron. And Kornbluh, Roy. “Recent Progress in Heel-strike Generators using
Electroactive Polymers.” www.darpa.mil/dso/thrust/md/energy/briefings/5sri.pdf
6)
Zorpette, Glenn. “Fly on the Wall.” Red Herring Magazine. October 2000.