One of the main technical challenges in the development of dielectric elastomer (DE) stack actuators is
the design and realization of suitable electrodes. They must be compliant and be able to undergo large
strains without adding too much stiffness. Metal electrodes are therefore normally out of question due to
their high stiffness, though their electrical properties are excellent. In this work a new design approach is
presented which comprises rigid metal electrodes. Its functionality is proven by means of numerical simulations
and experimental tests. It allows the customized tailoring of transducer elements due to the designable
electrode structure. A functional demonstrator is built and tested concerning its electrical, mechanical and
electromechanical behavior. For this new actuator type a full electromechanical model is developed. It contains
all transfer characterisitcs in a nonlinear description and accounts for various physical effects arising from the
special actuator design. Due to its standardized interface configuration it can well be used in combination
with existing models for mechanical structures and electrical amplifiers to completely model active systems.
It is applicable for the realistic simulation necessary in the development of active solutions with EAP devices.
A first longterm test with 108 load cycles was performed in order to show the durability of the actuator.
Dielectric elastomers (DE) have proved to have high potential for smart actuator applications in many laboratory
setups and also in first commercially available components. Because of their large deformation capability
and the inherent fast response to external stimulation they proffer themselves to applications in the field of
active vibration control, especially for lightweight structures. These structures typically tend to vibrate with
large amplitudes even at low excitation forces. Here, DE actuators seem to be ideal components for setting up
control loops to suppress unwanted vibrations. Due to the underlying physical effect DE actuators are generally
non-linear elements with an approximately quadratic relationship between in- and output. Consequently,
they automatically produce higher-order frequencies. This can cause harmful effects for vibration control on
structures with high modal density. Therefore, a linearization technique is required to minimize parasitic
effects. This paper shows and quantifies the nonlinearity of a commercial DE actuator and demonstrates the
negative effects it can have in technical applications. For this purpose, two linearization methods are developed.
Subsequently, the actuator is used to implement active vibration control for two different mechanical
systems. In the first case a concentrated mass is driven with the controlled actuator resulting in a tunable
oscillator. In the second case a more complex mechanical structure with multiple resonances is used. Different
control approaches are applied likewise and their impact on the whole system is demonstrated. Thus, the
potential of DE actuators for vibration control applications is highlighted.
KEYWORDS: Electroactive polymers, Actuators, Electrodes, Systems modeling, Resistance, Capacitors, Finite element methods, Electroluminescence, Instrument modeling, Chemical elements
The focus of this paper is on the modeling of dielectric elastomer actuators and generators. One of the effects
that is rarely considered in modeling of these systems is the influence of the materials' specific resistance on the
performance. The non-ideal electrical properties of both elastomer and electrode material will cause undesired
parasitic effects. Although for most laboratory scale prototypes these effects are hardly recognizable, they
may however play an important role for larger structures and especially for dynamic applications. Therefore,
an analytical model is developed and presented in this paper which can give helpful instructions for the design
and fabrication process of EAP-systems. It is proven to be valid by means of the finite element method and
subsequently extended for more complex systems.
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