scholarly journals In-Situ Fabrication of Composite Piezoelectric Wafer Active Sensors for Structural Health Monitoring

Aerospace ◽  
2004 ◽  
Author(s):  
Victor Giurgiutiu ◽  
Bin Lin
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Piezoelectric Composite ◽  
Active Sensors ◽  
In Situ Composite ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
In Situ Fabrication ◽  
Piezoelectric Wafer

Structural health monitoring (SHM) is important for reducing maintenance costs while increasing safety and reliability. Traditionally, structural integrity tests required attachment of sensors to the material surface. This is often a burdensome and time-consuming task, especially considering the size and magnitude of the surfaces measured (such as aircraft, bridges, structural supports, etc.). Temporary sensors are a hassle to install; there are some critical applications where they simply cannot accomplish the task required. Piezoelectric wafer active sensors (PWAS) can be permanently attached to the structure and offer a permanent sensor solution. Existing ceramic PWAS, while fairly accurate when attached correctly to the substance, may not provide the long term durability required for SHM. The bonded interface between the PWAS and the structure is often the durability weak link. Better durability may be obtained from a built-in sensor that is incorporated into the material. This paper describes the work on the in-situ fabrication of PWAS using a piezoelectric composite approach. The piezoelectric composite was prepared by mixing small lead zirconate titanate (PZT) particles in an epoxy resin matrix; the mixture was then directly applied onto the surface of a host structure using a designed mask. The curing of the piezo composite was carried out at elevated temperature. After curing, the cured composite was sanded down to the desired thickness. Finally, the piezo composite was poled under a high electric field to activate the piezoelectric effect. The resulting in-situ composite PWAS was utilized as a sensor for dynamic vibration and impact. Characterization of the in-situ composite PWAS on aluminum structure have been recorded and compared with ceramic PWAS before and after polarization. To evaluate the performance of the in-situ composite PWAS, both vibration and impact tests were conducted. In-situ composite PWAS are believed to be a good candidate for reliable low-cost sensor fabrication for SHM.

Impact Detection Using an Array of Piezoelectric Wafer Active Sensors and a Microcontroller Unit

2010 ◽  
Author(s):  
Abraham Light-Marquez ◽  
Andrei Zagrai
Keyword(s):  
Structural Health Monitoring ◽  
Sensor Network ◽  
Health Monitoring ◽  
Detection System ◽  
Active Sensors ◽  
Structural Health ◽  
Impact Detection ◽  
Piezoelectric Wafer Active Sensors ◽  
Piezoelectric Wafer ◽  
The Impact

This report discusses the development of an embeddable impact detection system utilizing an array of piezoelectric wafer active sensors (PWAS) and a microcontroller. Embeddable systems are a critical component to successfully implement a complete and robust structural health monitoring system. System capabilities include impact detection, impact location determination and digitization of the impact waveform. A custom algorithm was developed to locate the site of the impact.. The embedded system has the potential for additional capabilities including advanced signal processing and the integration of wireless functionality. For structural health monitoring applications it is essential to determine the extent of damage done to the structure. In an attempt to determine these parameters a series of impact tests were conducted using a ball drop tower on a square aluminum plate. The response of the plate to the impact event was recorded using a piezoelectric wafer sensor network attached to the surface of the plate. From this testing it was determined that several of the impact parameters are directly correlated with the features recorded by the sensor network.

scholarly journals Piezoelectric Wafer Active Sensors for Structural Health Monitoring of Composite Structures Using Tuned Guided Waves

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Victor Giurgiutiu
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Composite Structures ◽  
Guided Waves ◽  
Guided Wave ◽  
Impedance Method ◽  
Active Sensors ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
Piezoelectric Wafer

Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive transducers that enable a large class of structural health monitoring (SHM) applications such as: (a) embedded guided wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays; (b) high-frequency modal sensing, i.e., the electro-mechanical (E/M) impedance method; and (c) passive detection (acoustic emission and impact detection). The focus of this paper is on the challenges posed by using PWAS transducers in the composite structures as different from the metallic structures on which this methodology was initially developed. After a brief introduction, the paper reviews the PWAS-based SHM principles. It follows with a discussion of guided wave propagation in composites and PWAS tuning effects. Then, it discusses damage modes in composites. Finally, the paper presents some experimental results with damage detection in composite specimens. Hole damage and impact damage were detected using pitch-catch method with tuned guided waves being sent between a transmitter PWAS and a received PWAS. Root mean square deviation (RMSD) damage index (DI) were shown to correlate well with hole size and impact intensity. The paper ends with summary and conclusion; suggestions for further work are also presented.

Computational Setup of Structural Health Monitoring for Real-Time Thermal Verification

2011 ◽  
Author(s):  
Derek Doyle ◽  
Whitney Reynolds ◽  
Brandon Arritt ◽  
Brenton Taft
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Changes ◽  
Space Vehicles ◽  
Lap Joint ◽  
Active Sensors ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
Piezoelectric Wafer ◽  
Inspection Techniques

Research at the AFRL Space Vehicles Directorate is being conducted to reduce schedule times for assembly, integration, and test, to make satellite-based capabilities more responsive to user needs. Structural Health Monitoring has been pursued as a means for validating workmanship and has been proven on PnPSat-1. Embedded ultrasonic piezoelectric wafer active sensors (PWAS) have been utilized with local and global inspection techniques, developed both in house and by collaborating universities, to detect structural changes that may occur during assembly, integration, and test. Specific attention has focused on interface qualification. It is now reasonable to believe that evaluation of interfaces through the use of such sensors can also be used to indirectly qualify the structure thermally and that tedious thermal-vacuum testing may be truncated or eliminated altogether. This paper focuses on the computational development of extracting thermal properties from ultrasonic transmission records. Methods are validated on simple bolted lap-joint cantilever beams.

Structural Health Monitoring With Piezoelectric Wafer Active Sensors Exposed to Irradiation Effects

2012 ◽  
Author(s):  
Bin Lin ◽  
Matthieu Gresil ◽  
Victor Giurgiutiu ◽  
Adrian E. Mendez-Torres
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
High Energy ◽  
Pressure Vessels ◽  
Irradiation Effects ◽  
Nuclear Facilities ◽  
Active Sensors ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
Piezoelectric Wafer

The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS) such as pressure vessels and piping (PVP) in a nuclear reactor. Technologies for the diagnosis and prognosis of PVP systems can improve verification of the health of the structure that can eventually reduce the likelihood of inadvertently failure. Recently investigated piezoelectric wafer active sensors (PWAS) open the possibilities to develop and deploy such system. Piezoelectric wafer active sensors are widely used in structural health monitoring (SHM) to determine the presence of cracks, delaminations, disbonds, and corrosion. Durability and survivability of PWAS under environmental exposures has been tested before. However the irradiation effects, pertinent to nuclear facilities for PWAS, have not been studied yet. This paper presents a study on PWAS that exposed to high energy gamma radiation. PWAS were irradiated using a Co-60 gamma source in an irradiator with different exposure times. The dose rate and total absorbed dose were calculated using Monte Carlo simulations (MCNPX). The PWAS material properties, electrical contact change were characterized through a series of tests. The electro-mechanical impedance spectrum (EMIS) of PWAS was measured before and after irradiation. This study not only provides the fundamental understanding of the PWAS irradiation survivability but also tests the potential of PWAS as irradiation sensors for nuclear applications.

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