Degradation of piezoelectric properties of piezomaterials has long been a concern in the applications of actuators and sensors. In this work, alternating electric field induced fatigue crack growth and effect of cyclic electric field on piezoelectric property decay were characterized for a polarized PZT-PIC151. The results show that a relatively high alternating electric field drives the pre-existing microcracks to grow very fast initially due to the superposition of electrostriction induced stress and residual stress at the crack tip, then slow down gradually to becoming dormant. The butterfly loop evolution shows that cyclic electric field strongly degrades the piezoelectric properties due to the frequent domain switching. The output strain decays more than 50% after 106 electric cycles at 0.9 Ec for PIC 151 pellet bonded on an aluminum beam

Galea, S.

Mai, Y. W.

Ye, L.

Zhang, X. P.

University of Queensland eSpace

SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
Fatigue Crack Growth And Piezoelectric Property Decay Induced By Cyclic  
Electric Fields For An Actuation Piezoceramic 
X P Zhang∗1, 2, L Ye1, Y-W Mai1 and S. Galea3 
1Centre of Expertise in Damage Mechanics, School of Aerospace, Mechanical and  
Mechatronic Engineering, the University of Sydney, NSW 2006, Australia 
2 School of Mechanical Engineering, South China University of Technology,  
Guangzhou 510640, China  
3Air Vehicles Division, Platform Sciences Laboratory, DSTO,  
Melbourne, VIC 3001, Australia 
 
 
 
ABSTRACT: Degradation of piezoelectric properties of piezomaterials has long been a concern in the 
applications of actuators and sensors. In this work, alternating electric field induced fatigue crack growth and 
effect of cyclic electric field on piezoelectric property decay were characterized for a polarized PZT-PIC151. 
The results show that a relatively high alternating electric field drives the pre-existing microcracks to grow 
very fast initially due to the superposition of electrostriction induced stress and residual stress at the crack 
tip, then slow down gradually to becoming dormant. The butterfly loop evolution shows that cyclic electric 
field strongly degrades the piezoelectric properties due to the frequent domain switching. The output strain 
decays more than 50% after 106 electric cycles at 0.9 Ec for PIC 151 pellet bonded on an aluminum beam.  
1 INTRODUCTION  
Piezoelectric actuators and sensors have been successfully employed in a wide range of 
applications, such as micro-positioning, controlling structural shape and vibration, noise 
suppression and acoustic control etc (Newnham and Ruschau, 1991; Straub, 1996; Ting and 
Howarth, 1997). Most of the piezoelectric materials currently used are piezoceramics, such as lead 
zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT) and barium titanate (BaTiO3) 
etc. The actuators or sensors made of these piezoceramics offer large piezoelectric and dielectric 
coefficients, quick time response, compactness, low power consumption and so forth (Herbert, 
1982; Newnham et al., 1990; Newnham and Ruschau, 1991; Jiang et al., 1994; Sakai, 1999). 
However, there are two major disadvantages for these piezoceramics, that is, their intrinsic brittle-
ness and low strength subjected to mechanical stress, and the susceptibility of electromechanical 
properties to external applied electric load where it is known that electric field degrades remarkably 
piezoelectric properties of piezoceramics. In applications, the actuation structures or systems are 
subjected to very complicated service conditions of both high electric and mechanical stress fields. 
The anisotropy of fracture toughness and electric field induced fatigue crack growth in polarized 
piezoceramics have been recognised to affect significantly the service performance of actuators and 
sensors. The decay of piezoelectric properties and the degradation mechanisms of piezomaterials 
due to the strong coupling effect of high alternate electric field and mechanical load have been a 
serious concern, but have not been well characterised. In particular, durability performance of 
piezomaterials, in terms of integrity and piezoelectric properties, is always a key issue in long-term 
service for both conventional piezoceramics-based actuation systems and recently developed new 
generation actuation systems such as active fiber composites (AFC) and macro-fiber composite 
(MFC) actuators, as well as single crystal piezoelectric actuators/sensors (Krempl et al., 1997; 
Chiang et al., 1998; Park and Hackenberger, 2002). Especially, cyclic domain switching in piezo-
materials caused by the high frequency cyclic electric field and consequently the electric field 
induced fatigue-crack growth, and the temperature rise due to self-heating of the materials, would 
                                                 
∗Corresponding author. Fax: 086-20-87114484; Emails: mexzhang@scut.edu.cn or xzhang@aeromech.usyd.edu.au 
SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
seriously deteriorate the electromechanical properties of piezomaterials, in terms of an obvious 
decay of output strain and performance stability of piezoelectric effect (Weitzing et al., 1999; Park 
et al., 2000). However, these issues have not been well understood. Only limited experimental work 
had been performed to characterize the cyclic electric field induced fatigue crack growth behaviour 
and the decay of piezoelectric properties due to the application of an alternating electric field.   
In this work, the fatigue crack growth behaviour caused by a high cyclic electric field and its 
influence on piezoelectric property decay were characterized for a polarized PZT. The emphasis 
was placed on the characterization of the butterfly loop evolution due to electric field cycles for the 
PZT pellet bonded on an aluminum beam. 
 
2 MATERIALS AND EXPERIMENTAL PROCEDURE  
2.1 Piezoelectric material  
The piezoceramics used in this work was a type of lead zirconate titanate piezoceramic pellets (PIC 
151) produced by Physik Instrumente (PI GmbH & Co., Germany). PIC 151 could be compared 
with PZT-5H types in terms of electromechanical and dielectric parameters etc, and was used in 
many applications to replace PZT-5H. Its main technical parameters are shown in Table 1.   
 
Table 1. Main technical parameters of piezoelectric pellets PIC 151 (as received) 
Density ρ = 7.80 g/cm3 Dielectric constants: 033 /εε T =2100, 011 /εε T =1980  
Curie temperature: ~250 °C Maximum field in poling direction: 2000V/mm 
Young's Modulus: Y33 =52.6 GPa Coupling factors: kp=0.62, k33=0.69, k31=0.34 
Coercive field, Ec:  ~ 1000 V/mm Elastic constants: ES11 =66.7GPa,
ES33 =86.2 GPa  
Dielectric loss (tan δ): 15 ×10-3 Mechanical Q: 120  
 
2.2 Electric induced crack growth and piezo-property degradation evaluation experiment  
To characterize electric field induced fatigue crack growth, an experimental system was set up, see 
our early work (Zhang et al., 2004), where precracks were prepared on the anisotropic plane of a 
PZT pellet by Vickers indentation. In this work, electric induced crack growth was characterized 
under different electric fields. To evaluate the influence of electric field on piezoelectric properties, 
a measurement system was built up, see Fig.1, which consists of several modules: E1441A Signal 
Generator module, E1415A Algorithmic Close Loop Controller module, E1432A Digitiser and DSP 
module, etc. With E1441A Signal Generator module, voltage signals in different forms of sine, 
square, triangle etc, could be generated and sent to the PZT pellet. In this study, a sine waveform 
voltage signal (as the applied electric field) with a frequency of 0.05 Hz was applied to the pellet 
(25×20×1 mm) which was bonded on an aluminium beam (200 mm long, 25 mm wide and 1 mm 
thick) as in Fig.1. A standard strain gauge with a gauge factor of 2.08 was mounted on the pellet. 
E1415A Algorithmic Close Loop Controller module is designed to receive strain signal aided by an 
extra E511A Transient Strain Signal Conditioning Plug-on (SCP) from the strain gauge. The 
Transient Strain SCP forms a quarter-bridge measurement circuit together with the strain gauge, and 
provides 4-Chunnels strain measurements for the HP E1413 High Speed A/D Module. The piezo-
strain can be obtained directly from this system. With the acquisition of both applied electric field 
and responding output strain, the butterfly loops of the piezoceramic pellet were obtained. In 
measurements, the sampling rate was 10 points/second. To evaluate the influence of cyclic electric 
field on butterfly loop characteristics of PIC151, a sine wave electric field with a frequency of 50 
Hz was used. After a certain number of cycles, this alternating electric field was stopped in order to 
measure the butterfly loop evolution (i.e. the performance of output strain vs applied electric field). 
 
SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 1. Configuration of the experimental system. 
 
3 RESULTS AND DISCUSSION  
Figure 2 shows the growth rate of electric induced cracks versus crack length, with a peak-to-peak 
applied electric field intensity 85%Ec(Ec denotes coercive field). It is clear that the cracks grew very 
fast at the beginning, then slowed gradually down, and finally became dormant after a certain 
electric cycles (300,000). In general, the crack growth rate was very small, in the order of 10-11 
m/cycle. The initial fast crack growth within a short distance from the original indention crack tips 
is mainly due to the super-position of both tensile residual stress induced by the indentation and the 
mechanical stress caused by the piezoelectric effect under the high electric field. When the cracks 
propagated gradually beyond the tensile residual stress affected zone, the crack growth rates 
decreased, because the residual stress vanishes and the mechanical strain provided by the 
piezoelectric effect is the only driving force for crack growth.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 2. The electric field induced fatigue crack growth rate versus crack length. 
 
PC/NI 
Labview© 
Platform 
HP VXI 
Mainframe
Agilent© 
Piezo-  
Driver/ 
Amplifier 
E1441A Signal 
Generator 
Module 
E1432A Digitizer 
+ DSP Module  
E1511A 4-Channel 
Transient Strain 
SCP 
 
E1415A Algorithmic  
Close Loop Controller 
Module 
 
Strain gauge 
PZT bonded on Al beam 
 
Aluminum beam 
0.85 Ec, 50 Hz
0
1E-11
2E-11
3E-11
4E-11
5E-11
198 208 218 228
Crack length (µm)
da
/d
N 
(m
/c
yc
le
)
SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
Figure 3 shows the initial butterfly loop (i.e., output strain versus applied electric field) of the PIC 
151 pellet bonded on the aluminium beam without application of electric fatigue cycles. It clearly 
shows a typical butterfly loop feature indicating the switching of the electric polarization. The peak-
to-peak output strain is about 0.74 × 10-3. Figures 4 and 5 show the evolution of butterfly loops after 
1 × 105 and 1 × 106 electric field cycles, respectively, with the peak-to-peak electric field intensity 
of 0.9Ec. The collapse of the butterfly loop wings is obvious. This means the deterioration of piezo-
electric properties of the piezoceramics pellets.  
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 3.  The initial butterfly loop of PIC 151 pellet before electric fatigue. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 4. Butterfly loop change after 1 ×105 electric fatigue cycles at 0.9Ec. 
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-100
0
-800 -600 -400 -200 0 200 400 600 800 1000
Electric field [V/mm]
St
ra
in
 [1
E-
3]
No cyclic electric field 
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-1000 -800 -600 -400 -200 0 200 400 600 800 1000
Electric field [V/mm]
St
ra
in
 [1
E-
3]
After 105 cycles at 0.9Ec
SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 5. Collapse of butterfly loop wings after 1 ×106 electric fatigue cycles at 0.9Ec. 
 
Table 2 shows the piezo-property change, in terms of peak-to-peak output strain, due to the cyclic 
electric field. Comparing Figs. 3 to 5 and the data in Table 2, it is clear that the output strain 
decreases with electric field cycles. The peak-to-peak output strains decrease 50% after 1 × 106 
electric cycles with an electric field intensity 0.9Ec. The main reason for this apparent output strain 
decay may be caused by the cyclic electric fatigue, which strongly impedes switching of domains in 
these piezo-materials. The walls of the domains are pinned so that they remain in a preferred poling 
direction, which leads to the deterioration of piezoelectric properties of the piezo-materials. With no 
or little piezoelectric switching, the linear inverse piezoelectric effect causes most of the mechanical 
strain of cyclically loaded PZT pellets, which leads to the collapse of butterfly wings.  
 
Table 2. Peak-to-peak output strain decay due to cyclic electric field induced fatigue 
Initial strain (without electric cycles)                   0.74 × 10-3                     0    decay 
After 105 electric field cycles at 0.9Ec                 0.64 × 10-3                   14% decay  
After 106 electric field cycles at 0.9Ec                 0.36 × 10-3                  51%  decay  
 
From the microstructural viewpoint, a piezoelectric material is composed of many randomly 
oriented crystals or grains, and each of them has one or few domains. After polarization, the dipoles 
or domains tend to align themselves parallel to the poling direction, so that the piezo-material has a 
permanent (or remanent) polarization. However, not all domains or dipoles can align themselves 
along the poling direction. Under an alternating electric field, the domains or dipoles change their 
direction frequently being driven by the external electric field. The primary indication of fatigue, 
after a number of electric cycles, is the decrease of the remanent polarization Pr accompanied by a 
change in the coercive field, Ec. The mechanism of electric field induced fatigue of piezoceramics is 
the frequent switching of domains or dipoles in the material as shown in Fig.6. It has been agreed 
that switchable polarization is reduced so as to account for the decreased macroscopic polarization 
(Nuffer et al., 2000). Thus, some domains have to become inactive in the switching process. Fixed 
domains were recently observed by atomic force microscopy, and it was shown that the number of 
non-switching domains increased during cycling (Gruverman et al., 1996; Colla et al., 1998).  
Anyway, it is worth indicating that more studies on the role of microstructure in fatigue are needed.  
-0 .5
-0 .4
-0 .3
-0 .2
-0 .1
0
0.1
0.2
0.3
0.4
0.5
-100
0
-800 -600 -400 -200 0 200 400 600 800 1000
E lectric  fie ld  [V /m m ]
St
ra
in
 [1
E-
3]
A fter 106 cycles at 0 .9Ec
SIF2004 Structural Integrity and Fracture. http://eprint.uq.edu.au/archive/00000836 
  
 
 
 
 
 
 
 
 
Fig. 6. Domain switching caused by tensile stress field and cracking. 
 
4 CONCLUSIONS  
1)  A relatively high alternating electric field drives the pre-existing microcracks to grow initially 
very fast due to the superposition of electrostriction induced stress and residual stress at crack 
tip, then slow down gradually to become dormant. 
2)  Cyclic electric field deteriorates piezoelectric properties of piezoceramics due to the high cycle 
fatigue of domain switching. The output strain decays more than 50% after undergoing 1×106 
electric field cycles for a PZT PIC151 bonded on an aluminum beam.  
3)  The deterioration of piezo-properties is mainly due to the pinning effect of domains walls. The 
output strain decay of PZT is caused by the cyclic electric fatigue, which strongly impedes the 
switching of domains.  
4) The main mechanism of electric field induced fatigue of piezo-materials is frequent switching 
of domains or dipoles under cyclic electric fields. More in-depth research is needed.   
 
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Poling
direction 
90° domain switchingor


Fatigue Crack Growth And Piezoelectric Property Decay Induced By Cyclic Electric Fields For An Actuation Piezoceramic

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Fatigue Crack Growth And Piezoelectric Property Decay Induced By Cyclic Electric Fields For An Actuation Piezoceramic

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