Bo Li's blog

Electromechanical stability in charge-controlled dielectric elastomer actuation

Submitted by Bo Li on Tue, 12/13/2011 - 01:05

Theoretical investigation on polar dielectric with large electrocaloric effect as cooling devices

Submitted by Bo Li on Wed, 11/09/2011 - 04:41

research

Polar dielectric based cooling devices are
modeled as a system with two degrees of freedom and represented by either an
entropy-temperature or electric displacement-electric field plane. A typical
thermodynamic energy cyclic path is proposed for polar dielectric as cooling
devices to experience. With the influence of temperature taken into
consideration, the free energy of a thermal electrical coupling system of polar
dielectrics is formulated, and the variation of temperature and entropy, the
absorption of heat, and the work under different electric fields are calculated
for BaTiO3, Pb(ZrxTi1-x)O3, P(VDF-TrFE), and water. And the simulation results
obtained agree well with the recently published experimental data [B. Neese, et

A model for conditional polarization of the actuation enhancement of a dielectric elastomer

Submitted by Bo Li on Mon, 10/24/2011 - 11:00

research

electromechanical instability

dielectric elastomer

polarization

mechanical constrains

dielectric constant

NMR study on mechanisms of ionic polymer-metal composites deformation with water content

Submitted by Bo Li on Mon, 10/03/2011 - 15:33

research

deformation

IPMC

electroactive polymer

water content

Effect of temperature on the stability of dielectric elastomers

Submitted by Bo Li on Tue, 08/30/2011 - 13:03

Dielectric elastomer (DE) is a kind of electroactive polymer material,
capable of large deformation up to 380%. However, under conservative
operating conditions, DE is susceptible to instability with a small
deformation due to various modes of failure, including electrical
breakdown, electromechanical instability (EMI), loss of tension and
rupture by stretch. This paper proposes a free energy model in the
thermodynamic system of DE involving thermoelastic strain energy,
electric energy and purely thermal contribution energy to obtain the
stability conditions of all failure modes. The numerical results
indicate that the increase in temperature can markedly contribute to
improving the entropy production, the actuation stress and the critical

Polarization-modified instability and actuation transition of deformable dielectric

Submitted by Bo Li on Wed, 07/20/2011 - 15:15

research

Effect of mechanical pre-stretch on the stabilization of dielectric elastomer actuation

Submitted by Bo Li on Tue, 03/29/2011 - 14:31

A dielectric elastomer is capable of giant electromechanical actuation but fails at breakdown due to instability under certain conditions with a small deformation. By applying a mechanical pre-stretch, one obtains a stabilized large actuation.

Extension limit, polarization saturation, and snap-through instability of dielectric elastomers

Submitted by Bo Li on Fri, 01/21/2011 - 02:31

research

dielectric elastomer polarization saturation

A dielectric elastomer is capable of largevoltage-induced deformation, particularly when the voltage is applied on theverge of snap-through instability. Thispaper describes a model to show that the snap-through instability is markedlyaffected by both the extension limit of polymer chains and the polarizationsaturation of dipoles. The model mayguide the search for high-performance dielectric elastomer transducers.

International Journal of Smart and Nano Materials 2011 2 (2), 59-67