Environmental Engineering Reference
In-Depth Information
Positive
Live Wire
Ground
Wire
Piezoelectric
Push-Button
Igniter
FIGURE 4.3
A piezoelectric push-button igniter and its components.
external mechanical stress,
,isapplied by the spring-loaded hammer. The
short circuit charge displacement
Q
3
generated on the surface of the piezo-
electric generator of area
A
=
L
∗
W
along the axis-3 can be expressed as
Q
3
=
d
33
F
3
(4.3)
where
L
is the length along the axis-2 and
W
the width along the axis-1.
The applied stress,
,isafunction of the applied mechanical force,
F
, and the
surface area,
A
. The piezoelectric voltage constant,
g
,isthe quotient of the elec-
tric field, generated
E
, and the stress,
T
, applied [79]. Additionally, the elec-
tric field is a function of the open circuit voltage,
V
oc
,ofthe piezoelectric
generator divided by its thickness,
T
, hence the open circuit electric field
E
oc
generated [111] can be expressed as
V
oc,
3
t
g
33
F
3
A
E
=
=
(4.4)
F
+
+
+
Q
or
V
P
P
-
-
-
L
FIGURE 4.4
Parallel compression on a piezoelectric element. (Form Piezo Systems, Inc., “Introduction to
piezo transducers,”
http://www.piezo.com/tech2intropiezotrans.html
, accessed on May 17,
2010 [111].)
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