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The
piezoelectric properties are described by a system of
symbols and notations, identifying compliance,
electromechanical coupling, etc.
The
tables include the MKS units used in measuring each
property.
Also
see the later section on Units
& Symbols for a complete listing.
|
|
Ceramic
Property Definitions
| Property |
Definition |
MKS
Units |
| Electro
Mechanical Coupling Coefficient |
| k |
or... |
- |
 |
- |
| Piezoelectric
Constants |
| d |
 |
m
/ V |
 |
C
/ N |
| g |
 |
V
/ N |
 |
m2
/ C |
| Relative
Dielectric Constant |
| K |
 |
- |
| Modulus
of Elasticity |
| Y |
 |
Nm-2 |
| Density |
 |
 |
kg/m3 |
| Frequency
Constant |
| N |
Controlling
Dimension x Resonant Frequency |
Hz
m |
|
|
|
Superscript
and subscript notations describe the characteristics of a
property. The next table illustrates and explains several
examples of annotated symbols. The superscripts describe
external factors (physical mounting, electrical conditions,
etc.) that effect the piezoelectric property. The subscripts
describe the relationship of the property to the poling
axis.
The
characteristics of piezoelectric properties depend on their
orientation to the poling axis. This orientation determines
the direction of the action or response associated with the
property. The subscript notations define the axes of a
component in terms of orthogonal axes: 1 corresponds to the
x-axis, 2 corresponds to the y-axis, and 3 corresponds to
the z-axis. Conventionally, the direction of polarization is
defined as the 3 axis. (See right)
The
first subscript position identifies the direction of the
action; the second identifies the direction of the response.
For example, refer to the piezoelectric "d "
constant in the following table. The first subscript refers
to the direction of the field and the second refers to the
direction of the strain. For the converse piezoelectric
constant "g", the first refers to the stress and
the second to the voltage.
|
(4, 5 and
6 refer to shear strains) |
 |
indicates
that compliance is measured with electrode circuit
open |
| indicates
that stress or strain is in direction 1 |
| indicates
that strain or stress is in direction 1 |
| Compliance
= strain / stress |
|
|
 |
indicates
that compliance is measured with electrodes connected
together |
| indicates
that stress or strain is in shear around axis 3 |
| indicates
that strain or stress is in direction 3 |
| Compliance
= strain / stress |
|
|
 |
indicates
that all stresses on material are constant; for
example zero external forces |
| indicates
that electrodes are perpendicular to axis 1 |
| |
Relative
dielectric constant =  |
| |
|
|
|
 |
indicates
that all stresses on material are constant; for
example material completely blocked preventing
deformation in any direction |
| indicates
that electrodes are perpendicular to axis 3 |
| |
Relative
dielectric constant =  |
| |
|
|
|
 |
|
| indicates
that stress or strain is in shear around axis 2 |
| indicates
that electrodes are perpendicular to axis 1 |
| Electromechanical
coupling |
|
|
 |
Planar,
used only for thin discs. It indicates electrodes
perpendicular to axis 3 and stress or strain equal in
all directions perpendicular to axis 3. |
| |
| Electromechanical
coupling |
|
|
 |
|
| indicates
that the piezoelectric induced strain, or the applied
stress, is in direction 3 |
| indicates
that electrodes are perpendicular to axis 3 |
|
strain
applied stress
|
= |
short circuit charge / electrode
area
applied stress
|
|
|
|
 |
Indicates
that stress is applied equally in 1, 2 and 3
directions (hydrostatic stress; and that electrodes
are perpendicular to axis 3) |
| |
|
short circuit charge / electrode area
applied stress
|
|
|
 |
|
| indicates
that the applied stress or piezoelectric induced
strain is in direction 1 |
| indicates
that electrodes are perpendicular to axis 3 |
|
field
applied stress
|
= |
strain
applied charge / electrode area
|
|
|
|
 |
|
| indicates
that the applied stress or piezoelectric induced
strain is in shear form around axis 2 |
| indicates
that electrodes are perpendicular to axis 1 |
|
field
applied stress
|
= |
strain
applied charge / electrode area
|
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