Bo Li's blog

Dielectric elastomers (DEs) feature nonlinear dynamics resulting from an electromechanical coupling.

Under alternating voltage, the DE resonates with tunable performances. We present an

analysis of the nonlinear dynamics of a DE as electromechanical resonator (DEER) configured as a

pure shear actuator. A theoretical model is developed to characterize the complex performance

under different boundary conditions. Physical mechanisms are presented and discussed. Chaotic

A pre-stretched dielectric elastomer is capable of large deformation, when subject to voltage. This paper investigates the effect of two types of pre-stretch: by strain and by stress. The difference is compared and discussed using thermodynamics models. The significance of the pre-stretch in actuation is explained by examining the true stress in actuation. Under both pre-stretch strategies, during the actuation, the dielectric elastomer exhibits hysteresis loops due to snap-through but differs in shape and physical quantity.

Soft dielectric elastomer is able to generate an

electromechanical response in terms of reversible shape

changing, which is a muscle-like behavior. The deformation

and electromechanical stability of dielectric elastomers,

classified by their deformation modes, uniaxial extension,

equal biaxial expansion and pure shear, are investigated.

Pull-in instability occurs in equal biaxial and uniaxial modes

at a small stretch ratio, while the pure shear mode features

wrinkling instability after a large stable deformation. The

The dielectric constant is an essential electrical parameter to the
achievable voltage-induced deformation of the dielectric
elastomer. This paper primarily focuses on the temperature
dependence of the dielectric constant (within the range of 173 K
to 373 K) for the most widely used acrylic dielectric
elastomer (VHB 4910). First the dielectric constant was investigated
experimentally with the broadband dielectric spectrometer
(BDS). Results showed that the dielectric constant first increased
with temperature up to a peak value and then dropped to a
relative small value. Then by analyzing the fitted curves, the Cole–Cole
dispersion equation was found better to characterize the
rising process before the peak values than the Debye dispersion

The dielectric constant of elastomeric dielectric material is an
essential physical parameter, whose value may affect the
electromechanical deformation of a dielectric elastomer actuator. Since
the dielectric constant is influenced by several external factors as
reported before, and no certain value has been confirmed to our
knowledge, in the present paper, on the basis of systematical comparison
of recent past literature, we conducted extensive works on the
measurement of dielectric properties of VHB films, involving five
influencing factors: prestretch (both equal and unequal biaxial),
electrical frequency, electrode material, stress relaxation time and
temperature. Experimental results directly show that the dielectric