Piezoelectric wafer active sensors (PWAS) used in structural health monitoring (SHM) applications are able to detect structural damage using Lamb waves. PWAS are small, lightweight, unobtrusive and inexpensive. PWAS achieve direct transduction between electric and elastic wave energies. PWAS are essential elements in the Lamb-wave SHM with pitch-catch, pulse-echo, phased array system and electromechanical impedance methods. PWAS are charge mode sensors and they can be used as both transmitters and receivers. A model of PWAS is shown in this paper. In vibration, impact detections applications, the PWAS response is strong due to the large dynamic change of strain. In pitch-catch, pulse-echo and phased array applications, PWAS are used to generate and receive Lamb waves and the PWAS response is small. A charge amplifier for PWAS applications is introduced in this paper. PWAS are normally made of piezoceramic Lead Zirconate Titanate (PZT). The structural integrity tests require attachment of PWAS to the material surface and there are critical applications where the rigid piezoceramic wafers cannot conform to curved surfaces. As alternative one can use flexible piezopolymer such as polyvinylidene fluoride (PVDF); such PVDF-PWAS have been studied in this paper. PVDF-PWAS were mounted on a cantilever beam for the free vibration test and on a long rod for the longitudinal impact test. The experimental results of the PZT-PWAS and PVDF-PWAS have been compared with the conventional strain gauge. The theoretical and experimental results in this study gave the basic demonstration of the piezoelectricity of PZT-PWAS and PVDF-PWAS.

1.
Chang, F.-K. (1995) “Built-In Damage Diagnostics for Composite Structures,” in Proceedings of the 10th International Conference on Composite Structures (ICCM-10), Vol. 5, Whistler, B. C., Canada, August 14–18, 1995, pp. 283–289
2.
Chang, F.-K. (1998) “Manufacturing and Design of Built-in Diagnostics for Composite Structures,” 52nd Meeting of the Society for Machinery Failure Prevention Technology, Virginia Beach, VA, March 30–April 3, 1998.
3.
Wang, C. S.; Chang, F.-K. (2000) “Built-In Diagnostics for Impact Damage Identification of Composite Structures,” in Structural Health Monitoring 2000, Fu-Kuo Chang (Ed.), Technomic, 2000, pp. 612–621
4.
Lin
X.
;
Yuan
F. G.
(
2001
a) “
Diagnostic Lamb Waves in an Integrated Piezoelectric Sensor/Actuator Plate: Analytical and Experimental Studies
,”
Smart Materials and Structures
, Vol.
10
, 2001, pp.
907
913
5.
Lin, X; Yuan, F. G. (2001b) “Damage Detection of a Plate using Migration Technique,” Journal of Intelligent Material Systems and Structures, Vol. 12, No. 7, July 2001
6.
Ihn, J.-B.; Chang, F.-K. (2002) “Built-in diagnostics for monitoring crack growth in aircraft structures,” Proceedings of the SPIE’s 9th International Symposium on Smart Structures and Materials, 17–21 March 2002, San Diego, CA, paper #4702–04
7.
Giurgiutiu
V.
;
Zagrai
A.
(
2000
) “
Characterization of Piezoelectric Wafer Active Sensors
,”
Journal of Intelligent Material Systems and Structures
, Sage Pub., UK, Vol.
11
, No.
12
, December 2000, pp.
959
976
8.
Giurgiutiu, V.; Zagrai, A. N.; Bao J.; Redmond, J.; Roach, D.; Rackow, K. (2002) “Active Sensors for Health Monitoring of Aging Aerospace Structures,” International Journal of the Condition Monitoring and Diagnostic Engineering Management, UK, Vol. 5, No. 3, August 2002
9.
Giurgiutiu, V.; Bao, J.; Zhao, W. (2003) “Piezoelectric-Wafer Active-Sensor Embedded Ultrasonics in Beams and Plates,” Experimental Mechanics, Sage Pub. December 2003, pp. 428–449
10.
Pomirleanu, R.; Giurgiutiu, V. (2003) “Full-Power Dynamic Characterization of Piezoelectric and Magnetostrictive Actuators,” Journal of Intelligent Material Systems and Structures, Sage Pub. (in press)
11.
Giurgiutiu, V.; Zagrai, A.; Bao, J. (2004) “Damage Identification in Aging Aircraft Structures with Piezoelectric Wafer Active Sensors,” Journal of Intelligent Material Systems and Structures, Sage Pub., Vol. 15, No. 6, June 2004 (in press)
12.
Zhang, Y., “Dynamic Strain Measurement Using Piezoelectric Paint,” 4th International Workshop on Structural Health Monitoring, September 15–17, 2003, Stanford University, CA, pp. 1446–1452
13.
Heyliger
p.
, (
2004
) “
Two-Dimensional Static Field in Magneto-electro-elastic Laminates
,”
Journal of Intelligent Material Systems and Structure
, Vol.
15
pp.
689
709
, 2004
14.
Benveniste
Y.
(
1995
) “
Magnetoelectric Effect in Fibrous Composites with Piezoelectric and Piezomagnetic phases
,”
Phys. Rev. B.
,
51
;
16424
16427
15.
Giurgiutiu, V., “Micromechatronics Modeling, Analysis, and Design with Matlab,” CRC Press (2004)
16.
Giurgiutiu
V.
;
Jichi
F.
;
Berman
J.
;
Kamphaus
J.
(
2001
) “
Theoretical and Experimental Investigation of Magnetostrictive Composite Beams
,”
Smart Materials and Structures
, IOP Publishers, UK, Vol,
10
, No.
5
, October 2001, pp.
934
945
17.
Measurement Specialties, “Piezo Film Sensors Technical Manual,” 1998
18.
Whitney, S., “Vibrations of Cantilever Beams: Deflection, Frequency, and Research Uses,” 1999
19.
Voltera, L., Zachmanoglou, E. C. Dynamics of Vibrations. Columbus, Charles E. Merrill Books, Inc., 1965.
20.
Karl F, Graff, Wave Motion in Elastic Solids, N. Y., 1991
21.
Doyle, J. F., “Impact and Longitudinal Wave Propagation,” Experimental Techniques, 1998.
22.
Hamamatsu, “Characteristics and use of charge amplifier,” Solid State Division
This content is only available via PDF.
You do not currently have access to this content.