Dielectric elastomers, or more precisely dielectric polymers, are a relatively new class of
materials for variable-stiffness and variable-damping devices. Dielectric elastomers offer significant
potential advantages compared with previous variable stiffness smart materials. Advantages include
simplicity, broad dynamic range, ability to reach zero stiffness, low cost, minimal mass, shock
tolerance, simple drive circuitry, and design flexibility.
Dielectric elastomer devices in the variable-stiffness mode convert electrical and mechanical energy
back and forth to change mechanical impedance. This type of electromechanical transduction
distinguishes the variable stiffness mode from simply using a dielectric elastomer actuator to alter
the geometry, and hence the stiffness, of the device. Stiffness using a variable-stiffness mode
depends heavily on the electrical loading of the dielectric elastomer. Analysis shows that a constant
voltage loading reduces stiffness, down to zero in some cases, while a constant charge loading
increases stiffness.
Many applications can be considered for dielectric elastomer variable-stiffness mode such as
vibration control, suspensions, and tuning consumer devices for user comfort or preference. As with
dielectric elastomer actuators and generators, silicones and acrylics are the most promising
materials for variable-stiffness-mode devices.
