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Influence of geometry and material properties on the optimum performance of the C-shape piezo-composite actuator
Author(s)
Mtawa, Alexander Nikwanduka
Date Issued
2008
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
In recent years, due to rapid advances in technology there has been an increasingly high
demand for large displacement and large force, precise positioning, fast response, low power
consuming miniature piezoelectric actuators.
In certain smart structure applications, the use of curved piezoelectric actuators is necessary.
The present work extends the earlier investigations on the C- shape actuator by providing a
detailed investigation on the influence of geometric and material properties of the individual
layers of the C-shape piezocomposite for its optimal performance as an actuator.
Analytical models have. been used to optimize the geometry of the actuator. Experimental
and finite element analyses (using general purpose finite element software i.e.
CoventerWare and MSC. Marc) have been used for validation.
The present work has established that, by maintaining the thickness of the substrate and
piezoceramic layers constant; changing the external radius, for example increasing it, the
stiffness of the structure decreases and thus yielding large displacement This has a negative
effect on the force produced by the actuator.
With fixed thickness of the substrate and varying the thickness of the piezoceramic (for fixed
external radius) the result is as follows: Increasing the thickness of the piezoceramic layer
has the effect of decreasing the displacement while the force increases.
With fixed PZT thickness as well as the external radius, varying the substrate thickness has
the following effect: As the thickness of the substrate increases the displacement increases
reaching a maximum. Subsequent increase in the thickness of the substrate the
displacement is reduced. The force continues increasing at least for the ratios up to 1.0,
further increase of the substrate, subsequent decrease of force is also noted. In addition to
changing the thickness of the substrate, the choice of different material for the substrate has
the following effect: For substrate/PZT ratios of up to 0.6. an actuator with substrate material
having higher elastic modulus will produce larger displacement while for ratios beyond this
ratio the situation is reversed. The causes for this kind of behaviour have been addressed.
In all cases both force and displacement are found to be directly proportional to applied
voltage.
demand for large displacement and large force, precise positioning, fast response, low power
consuming miniature piezoelectric actuators.
In certain smart structure applications, the use of curved piezoelectric actuators is necessary.
The present work extends the earlier investigations on the C- shape actuator by providing a
detailed investigation on the influence of geometric and material properties of the individual
layers of the C-shape piezocomposite for its optimal performance as an actuator.
Analytical models have. been used to optimize the geometry of the actuator. Experimental
and finite element analyses (using general purpose finite element software i.e.
CoventerWare and MSC. Marc) have been used for validation.
The present work has established that, by maintaining the thickness of the substrate and
piezoceramic layers constant; changing the external radius, for example increasing it, the
stiffness of the structure decreases and thus yielding large displacement This has a negative
effect on the force produced by the actuator.
With fixed thickness of the substrate and varying the thickness of the piezoceramic (for fixed
external radius) the result is as follows: Increasing the thickness of the piezoceramic layer
has the effect of decreasing the displacement while the force increases.
With fixed PZT thickness as well as the external radius, varying the substrate thickness has
the following effect: As the thickness of the substrate increases the displacement increases
reaching a maximum. Subsequent increase in the thickness of the substrate the
displacement is reduced. The force continues increasing at least for the ratios up to 1.0,
further increase of the substrate, subsequent decrease of force is also noted. In addition to
changing the thickness of the substrate, the choice of different material for the substrate has
the following effect: For substrate/PZT ratios of up to 0.6. an actuator with substrate material
having higher elastic modulus will produce larger displacement while for ratios beyond this
ratio the situation is reversed. The causes for this kind of behaviour have been addressed.
In all cases both force and displacement are found to be directly proportional to applied
voltage.
Additional information
Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2008
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