CP620, Shock Compression of Condensed Matter - 2001
edited by M. D. Furnish, N. N. Thadhani, and Y. Horie
2002 American Institute of Physics 0-7354-0068-7
OUTPUTS OF SHOCK-LOADED SMALL PIEZOCERAMIC DISKS
Jacques A, Charestl and Jonathan Lee Mace 2
President ofDynasen Inc, 20 Arnold Place, Goleta, CA 93117
DX-2, Los Alamos National Laboratory, Los Alamos, NM 87545
2
Abstract. Thin small-diameter polycrystalline Lead-Zirconate-Titanate piezoceramic disks were shock
loaded in the DSS orientation over a stress range of 0.1-30 GPa. Their electrical outputs were
discharged into 50 Q viewing resistors, producing typically 0.15 [is quasi-triangular impulses ranging
from 50-700 V. The gas gun flat plate impact approach and the high explosives (HE) plane wave lens
approach were used to load piezoceramic elements. These piezoceramic elements consisted of 0.25 mm
thick and 1.32 mm diameter disks that were ultrasonically machined from 25 mm piezocrystal disks of
type APC 850, commercially produced by American Piezo Ceramic Inc. To facilitate our experiments,
the piezoceramic elements were coaxially mounted at the tip of a 2.35 mm diameter brass tube, an
arrangement that is commercialized by Dynasen, Inc. under the name Piezopin of model CA-1136.
Simple calculations on the electrical outputs produced by these piezoceramic disks reveal electrical
outputs in excess of 3000 W. Such short bursts of electrical energy have the potential for numerous
applications where critical timing is needed to observe fast transient events.
capable of producing a short-duration high-output
electrical signal when impacted by a fast moving
object, a shock wave or a strong blast.
INTRODUCTION
The use of piezoceramic materials has virtually
exploded over the past 20 years. Indeed, to describe
all their applications would require numerous
publications. This company, being a manufacturer
and developer of shock sensors, has of course
utilized various types of piezoelectric materials to
construct many of its sensors.
As several
experimenters know, we have supplied our sensors
to nearly all US DOE and DOD laboratories and to
several oversea research organizations engaged in
fundamental research of shock physics or
ammunition testing. One of our particular products,
which we call the Piezopin, has been used
intensively by shock wave physicists over the past
thirty years because of its low cost and high output
performance reliability.
To date, Piezopins have been utilized primarily for
event timing and triggering of instrumentation.
Despite their great popularity at many research
laboratories, relatively little quantitative
information has been published on their output
performance under shock wave loading or on
potential applications.
This particular study is concerned with the highoutput short-duration impulse capability of small
piezoceramic elements. The experiments presented
in this paper focus on results obtained by utilizing
Dynasen s Piezopin configuration when subjected
to a wide range of dynamic loads. Two series of
controlled tests were conducted to investigate the
output of these Piezopins. The first series of tests
was conducted at Dynasen s impact facility using
gas gun-driven plane wave impact tests of 0-10
A Piezopin is a small and simple coaxial device that
utilizes a thin piezoceramic disk as its detector. It is
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Eleven gas gun tests and six HE plane wave lens
tests were performed, each consisting of six to eight
Piezopins, plus several of Dynasen s Carbon Film
or Low Impedance Manganin gauges, depending on
the pressure range, for accurate recording of shock
pressure and shock arrival times. Standard shock
matching techniques were used to calculate
pressure in Teflon gauge packages.
GPa, whereas the second series of tests, 10-30 GPa,
was conducted at Los Alamos National Laboratory
(LANL) using HE lenses. The experimental
approach for these tests is described next, followed
by a brief data summary and some conclusions.
EXPERIMENTAL APPROACH
The intent of these experimental series was to
develop well characterized small, passive gauge
elements that can be used in applications where
critical timing information from fast transient
events is transmitted to a receiver from an antenna
or wave guide. These experiments demonstrated
that short, high power bursts of electrical energy
from small dipolar piezoceramic disks potentially
satisfied these requirements. Also, they provided
Hugoniot data up to about 80 kbar. In the
experiments reported Piezopins were oriented such
that the surface of a small dipolar piezoceramic
disk was parallel to an incident shock. When shock
loaded, this dipolar separation of charge is
compressed on the time scale of shock dynamics,
thereby producing a large electrical impulse across
50 Q that is recorded onto various digitizers via
coaxial cable.
Figure 1 shows the basic construction of Dynasen s
Piezopin, whereas Figures 2-3 illustrate the gas gun
and HE testing approaches.
Target Assembly
FIGURE 2. Typical gas gun assembly; 0-10 GPa. A flyer,
mounted on the front of a projectile, is fired from a gas gun into
the target assembly at normal incidence to the piezopins. Each
target assembly typically consisted of multiple Piezopins and
Carbon Film gauges.
Figure 2 illustrates the typical gas gun flyer and
target assemblies utilized in experiments at
Dynasen s impact facility. During initial
experiments we began to observe large variations in
(P9V) data points as successive tests in this
experimental series produced higher impact
pressures; where P is pressure and V is voltage
across 50 Q.
Thin wall
nrass tube
0.093"xl"
Our initial guess as to why this variation occurred
had to do with the fact that a small copper film was
vapor deposited over the front surface of the
Piezopin in order to form a complete circuit (Fig.
1). The large voltage spikes that developed over the
circuit (3000 W average power) caused us to
believe that the integrity of this thin film of copper
was questionable over the duration of the pulse.
Therefore, this copper film was replaced by a thin
copper disk. This resulted in only slightly better
data.
pei0ci*ramic disk
" O.Q52"x0.01Q"
FIGURE 1. Construction of the Dynasen Piezopin. The
piezoceramic disk contains a dipolar charge separation and is the
active element. The surface of this element is grounded to the
brass tube via a thin Cu disk, and the backside is connected to
the brass rod, thus providing a convenient arrangement for
coaxial transmission of the electrical impulse induced by the
incident shock.
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We now realize that this measured scatter in data
(see Fig. 6) probably results from dipolar variations
between individual piezoceramic disks. These
small disks were ultrasonically machined from
much larger piezoceramic crystals with no control
over variations in dipolar properties. Nevertheless,
the significant measured outputs of these small
passive elements should be noted.
Figure 4 is on the order of O.l-jJs. This time is
related to shock transit time in the piezoceramic
material.
A simple Gaussian is fit to this data in order to
illustrate the average power and frequency content
(Fig. 5) of a typical pulse. These frequencies are
such that electromagnetic transmission through air
and time resolved reception should be viable.
Typical Pube
Voltage accrass 5K1
Gaussian Fit:
Average Power:
; i
p (£ ( t ) ) 2
t2 - ti jt;
(R = 50 Q)
ddt
=2125 W
FIGURE 4. Typical pulse from a shocked 0.052 inch x 0.010
inch piezoceramic element. A Gaussian is fit to the data and is
used to illustrate the average power and frequency content of a
typical pulse.
| x 10~4
Fourier Transform of the Ganssian Fit
FIGURE 3. HE plane wave assembly; 10-30 GPa. A 4 inch
plane wave lens produces a flat detonation wave in the HE
booster material, which in turn produces a flat shock in the
attenuation package that becomes incident on the Teflon. The
gauge plane consists of an array of piezoceramic elements and
low impedance Manganin gauges. A Faraday cage is used to
isolate the gauge plane and cables from electrical noise inherent
in the detonation front.
1.25
1
0.75
0.5
0.25
0
Figure 3 illustrates the HE plane wave lens
experimental arrangement. In each experiment both
the 1/2 inch booster and the attenuation pack were
chosen such that the shock matched pressure
transmitted into the Teflon gauge package varied
from 10 to 30 GPa. This pressure was verified
using low impedance Manganin gauges.
FIGURE 5. Frequency content of a typical pulse from a shocked
piezoceramic element.
Figures 6-7 provide a summary of measured peak
output voltage across 50 Q and measured Hugoniot
data. The data of Figure 6 demonstrate that peak
pulse voltages from 300 to 700 V can be expected
over a range of about 20 to 350 kbar. Notice the
large scatter in data. We think this scatter is largely
Figures 4-5 illustrate a typical pulse whereas
Figures 6-7 provide a summary of measured data.
Notice that the duration of the pulse illustrated in
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due to dipolar variations between piezoceramic
elements. We expect that this scatter is due to
polycrystaline nature of material, a property that is
not detectable by the Hugoniot measurements of
Figure 7.
CONCLUSIONS
These experiments demonstrate that a small,
passive piezoceramic element can produce a highpower pulse over frequencies of up to 1-200 MHz
when shock loaded. There are, of course, many
potential applications that can be imagined for such
small, non-intrusive, passive elements. In
particular, electromagnetic transmission through air
should be viable.
APC 850: peak voltage across 50O
Furthermore, we suspect that the development of a
method for producing consistent dipolar
characteristics between individual piezoceramic
elements should eliminate much of the data scatter
seen on Figure 6. Further investigations on the
subject are expected to yield more insights on the
process of shock loading APC 850 polycrystal
piezopceramic.
FIGURE 6. Peak voltage output of shock loaded 0.052 x
0.010 piezoceramic elements. Each point represents the output
average of 6 or 8 piezopins.
ACKNOWLEDGEMENTS
This work was funded under Los Alamos National
Laboratory contract numbers 100554-001, 100554009X and 16326-001-009X.
REFERENCES
0.2
0.4
0.6
0.8
Particle Velocity (mm\jo,s)
Stanley P. Marsh, Editor. LASL Shock
Hugoniot Data, Publisher: University of
California Press, 1980
FIGURE 7. APC 850 Lead-Zirconate-Titanate Hugoniot
measurements (p=1.5 glee) and Lead-Zirconium-Titanate
(p=l.H4 glee} data from the LASL Shock Hugoniot Data
handbook.
Figure 7 provides six measured Hugoniot points of
APC 850 over a range of 0-80 kbar. The slope of
the resulting line is about 268 kbarl(mml s ). These
results were obtained from gas gun tests performed
at Dyansen, and are the first published results for
APC 850 that we are aware of (1).
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