Durability and Survivability of Piezoelectric Wafer Active Sensors on Metallic Structure

Abstract

Piezoelectric wafer active sensors are small, inexpensive, noninvasive, elastic wave generators/receptors that can be easily affixed to a structure. Piezoelectric wafer active sensor installation on the health-monitored structure is an important step that may have significant bearing on the success of the health monitoring process. The purpose of this paper is to explore the durability and survivability issues associated with various environmental conditions on piezoelectric wafer active sensors for structural health monitoring. The durability and survivability of the piezoelectric wafer active sensor transducers under various exposures (cryogenic and high temperature, temperature cycling, outdoor environment, operational fluids, large strains, fatigue load cycling) were considered over a long period of time. Both free piezoelectric wafer active sensors and bonded piezoelectric wafer active sensors on metallic structural substrates were used. Different adhesives and protective coatings were compared to find the candidate for piezoelectric wafer active sensor application in structural health monitoring. In most cases, piezoelectric wafer active sensors survived the tests successfully. The cases when piezoelectric wafer active sensors did not survive the tests were closely examined and possible causes of failure were discussed. The test results indicate that lead zirconate titanate piezoelectric wafer active sensors can be successfully used in a cryogenic environment; however, it does not seem to be a good candidate for high temperature. Repeated differential thermal expansion and extended environmental attacks can lead to piezoelectric wafer active sensor failure. This emphasizes the importance of achieving the proper design of the adhesive bond between the piezoelectric wafer active sensor and the structure, and of using a protective coating to minimize the ingression of adverse agents. The high-strain tests indicated that the piezoelectric wafer active sensors remained operational up to at least 3000 microstrain and failed beyond 6000 microstrain. In the fatigue cyclic loading, conducted up to 12 millions of cycles, the piezoelectric wafer active sensor transducers sustained at least as many fatigue cycles as the structural coupon specimens on which they were installed. State of the Art Piezoelectric wafer active sensors can send and receive ultrasonic Lamb waves and determine the presence of cracks, delaminations, disbands, and corrosion. In recent years investigators (Chang [1,2],

Cost-Effectiveness of Structural Health Monitoring in Fuselage Maintenance of the Civil Aviation Industry †

“…Lin et al [43] also tested the performance of PWAS under different temperatures. Different from the previous experiment, a free PWAS and bonded PWAS were tested at the same time, and the characterization method was electromechanical impedance.…”

“…For a corrosion environment, different solution environments are simulated [43]. They include saline solution, different types of hydraulic fluid, lubricating oil, and kerosene.…”

“…Lin et al [43] used a PWAS bonded to a 2024-T3 aluminum plate under tensile loading. Significant impedance change was observed after 3000 microstrains and this change became stronger after 6000 microstrains and failed around 7200 microstrains.…”

Developing a structural health monitoring system for nuclear dry cask storage canister

“…Our previous research has successfully demonstrated the use of PWAS on thick steel components and investigated the durability and survivability of the PWAS transducers under various exposures (cryogenic and high temperature, temperature cycling, freeze-thaw, outdoor environment, operational fluids, large strains, fatigue load cycling) [11] . In most cases, the PWAS survived the tests successfully.…”

Simultaneous Influence of Static Load and Temperature on the Electromechanical Signature of Piezoelectric Elements Bonded to Composite Aeronautic Structures

“…In an aeronautic context, temperature variations as well as static loads induced on the structure during a flight can both be very important. Experiments have been carried out that focused on temperature [5][6][7][8][9][10][11][12][13][14][15][16][17] or static loads [18][19][20][21][22], but rarely simultaneously [23][24][25][26]. Regarding temperature effects, it has been observed that the effect of temperature changes consists of a shift of the piezoelectric resonance frequencies.…”