Piezoelectric Wafer Embedded Active Sensors for Aging Aircraft Structural Health Monitoring (original) (raw)
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Damage identification in aging aircraft structures with piezoelectric wafer active sensors
2004
Piezoelectric wafer active sensors can be applied to aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. Two main detection strategies are considered: (a) the wave propagation method for far-field damage detection; and (b) the electro-mechanical (E/M) impedance method for near-field damage detection. These methods are developed and verified on simple-geometry specimens, and then tested on realistic aging-aircraft panels with seeded cracks and corrosion. The specimens instrumentation with piezoelectric-wafer active sensors and ancillary apparatus is presented. The experimental methods, signal processing, and damage detection algorithms, tuned to the specific method used for structural interrogation, are discussed. In the wave propagation approach, the pulse-echo and acousto-ultrasonic methods were considered. Reflections from seeded cracks were successfully recorded. In addition, acoustic emission and low-velocity impact were also detected. In the E/M impedance method approach, the high-frequency spectrum is processed using overall-statistics damage metrics. The (1-R 2 ) 3 damage metric, where R is the correlation coefficient, was found to yield the best results. The simultaneous use of the E/M impedance method in the near field and of the wave propagation method in the far field opens the way for a comprehensive multifunctional damage detection system for aging aircraft structural health monitoring.
2001
1 Piezoelectric wafer active sensors can be applied on aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. Two main detection strategies are considered: (a) the electro-mechanical (E/M) impedance method for near-field damage detection; and (b) the wave propagation method for far-field damage detection. These methods are developed and verified on simple-geometry specimens, and then tested on realistic aging-aircraft panels with seeded cracks and corrosion. The instrumentation of these specimens with piezoelectric-wafer active sensors and ancillary apparatus is presented. The experimental methods, signal processing, and damage detection algorithms, tuned to the specific method used for structural interrogation, are discussed. In the E/M impedance method approach, the high-frequency spectrum is processed using overall-statistics damage metrics. The (1-R) damage metric, where R is the correlation coefficient, was found t...
Title: Damage Identification in Aging Aircraft Structures with Piezoelectric Wafer Active Sensors
2016
1 Piezoelectric wafer active sensors can be applied on aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. Two main detection strategies are considered: (a) the electro-mechanical (E/M) impedance method for near-field damage detection; and (b) the wave propagation method for far-field damage detection. These methods are developed and verified on simple-geometry specimens, and then tested on realistic aging-aircraft panels with seeded cracks and corrosion. The instrumentation of these specimens with piezoelectric-wafer active sensors and ancillary apparatus is presented. The experimental methods, signal processing, and damage detection algorithms, tuned to the specific method used for structural interrogation, are discussed. In the E/M impedance method approach, the high-frequency spectrum is processed using overall-statistics damage metrics. The (1-R2)3 damage metric, where R is the correlation coefficient, was found...
Aircraft Structural Health Monitoring
2014
ABSTRACT: Piezoelectric wafer active sensors can be applied to aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. Two main detection strategies are considered: (a) the wave propagation method for far-field damage detection; and (b) the electro-mechanical (E/M) impedance method for near-field damage detection. These methods are developed and verified on simple-geometry specimens, and then tested on realistic aging-aircraft panels with seeded cracks and corrosion. The specimens instrumentation with piezoelectric-wafer active sensors and ancillary apparatus is presented. The experimental methods, signal processing, and damage detection algorithms, tuned to the specific method used for structural interrogation, are discussed. In the wave propagation approach, the pulse-echo and acousto-ultrasonic methods were considered. Reflections from seeded cracks were successfully recorded. In addition, acoustic emission and low-ve...
Structural Health Monitoring of Composite Structures with Piezoelectric-Wafer Active Sensors
AIAA Journal, 2011
Piezoelectric Q2 wafer active sensors are lightweight and inexpensive enablers for a large class of structural health monitoring applications such as 1) embedded guided-wave ultrasonics, i.e., pitch-catch, pulse-echo, and phased arrays; 2) high-frequency modal sensing, i.e., the electromechanical impedance method; and 3) passive detection (acoustic emission and impact detection). The focus of this paper will be on the challenges and opportunities posed by use of piezoelectric-wafer active sensors for structural health monitoring of composite structures as different from that of the metallic structures on which this methodology was initially developed. After a brief introduction, the paper discusses damage modes in composites. Then it reviews the structural health monitoring principles based on piezoelectric-wafer active sensors. This is followed by a discussion of guided-wave propagation in composites and how piezoelectric-wafer active sensor tuning can be achieved. Finally, the paper presents some damage detection results in composites: 1) hole damage in unidirectional and quasi-isotropic plates and 2) impact damage in quasiisotropic plates. The paper ends with conclusions and suggestions for further work.
Embedded Active Sensors for In-Situ Structural Health Monitoring of Thin-Wall Structures
Journal of Pressure Vessel Technology, 2002
The use of embedded piezoelectric-wafer active-sensors for in-situ structural health monitoring of thin-wall structures is presented. Experiments performed on aircraft-grade metallic specimens of various complexities exemplified the detection procedures for nearfield and far-field damage. For near-field damage detection, the electro-mechanical (E/M) impedance method was used. Systematic experiments conducted on statistical samples of incrementally damaged specimens were followed by illustrative experiments on realistic aging aircraft panels. For far-field damage detection, guided ultrasonic Lamb waves were utilized in conjunction with the pulse-echo technique. Systematic experiments conducted on aircraft-grade metallic plates were used to develop the method, while experiments performed on realistic aging-aircraft panels exemplified the crack detection procedure.
Structural Health Monitoring and Damage Detection with Piezoelectric Wafer Active Sensors
Most structural health monitoring and damage detection strategies utilize dynamic response information to identify the existence, location, and magnitude of damage. Traditional model-based techniques seek to identify parametric changes in a linear dynamic model, while non-model-based techniques focus on changes in the temporal and frequency characteristics of the system response. Because restoring forces in base-excited structures can exhibit highly non-linear characteristics, non-linear model-based approaches may be better suited for reliable health monitoring and damage detection. This paper presents the application of a novel intelligent parameter varying (TPY) modeling and system identification technique, developed by the authors, to detect damage in base-excited structures. This TPY technique overcomes specific limitations of traditional model-based and non-model-based approaches, as demonstrated through comparative simulations with wavelet analysis methods. These simulations confirm the effectiveness of the TPY technique, and show that performance is not compromised by the introduction of realistic structural non-linearities and ground excitation characteristics.
Recent Advances in Piezoelectric Wafer Active Sensors for Structural Health Monitoring Applications
Sensors
In this paper, some recent piezoelectric wafer active sensors (PWAS) progress achieved in our laboratory for active materials and smart structures (LAMSS) at the University of South Carolina: http: //www.me.sc.edu/research/lamss/ group is presented. First, the characterization of the PWAS materials shows that no significant change in the microstructure after exposure to high temperature and nuclear radiation, and the PWAS transducer can be used in harsh environments for structural health monitoring (SHM) applications. Next, PWAS active sensing of various damage types in aluminum and composite structures are explored. PWAS transducers can successfully detect the simulated crack and corrosion damage in aluminum plates through the wavefield analysis, and the simulated delamination damage in composite plates through the damage imaging method. Finally, the novel use of PWAS transducers as acoustic emission (AE) sensors for in situ AE detection during fatigue crack growth is presented. Th...
Structural Health Monitoring, 2005
The use of the electro-mechanical (E/M) impedance method for health monitoring of thin plates and aerospace structures is described. As a nondestructive evaluation technology, the E/M impedance method allows us to identify the local dynamics of the structure directly through the E/M impedance signatures of piezoelectric wafer active sensors (PWAS) permanently mounted to the structure. An analytical model for 2-D thin-wall structures, which predicts the E/M impedance response at PWAS terminals, was developed and validated. The model accounts for axial and flexural vibrations of the structure and considers both the structural dynamics and the sensor dynamics. Calibration experiments performed on circular thin plates with centrally attached PWAS showed that the presence of damage modifies the high-frequency E/M impedance spectrum causing frequency shifts, peak splitting, and appearance of new harmonics. Overall-statistics damage metrics and probabilistic neural network (PNN) are used to classify the spectral data and identify damage severity. On thin-wall aircraft panels, the presence of damage influences the sensors E/M impedance spectrum. When crack damage is in the PWAS medium field, changes in the distribution of harmonics take place and when crack damage is in the PWAS near field, changes in both the harmonics and the dereverberated response are observed. These effects are successfully classified with PNN and overall-statistics metrics, respectively. This proves that permanently attached PWAS in conjunction with the E/M impedance method can be successfully used in structural health monitoring to detect the presence of incipient damage through the examination and classification of the high-frequency E/M impedance spectra.
2006
Structural health monitoring (SHM) is important for reducing maintenance costs while increasing safety and reliability. Piezoelectric wafer active sensors (PWAS) used in 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. This paper starts with the state of the art on the impedance method for PWAS applications. Then, finite element impedance model for free and bonded PWAS with different sizes and shapes will be given. Experiments showed that the real part and imaginary part of PWAS had different usage. Applications of impedance-based structural health monitoring indicate impedance method as a good candidate for damage detection and sensor durability verification for SHM smart sensor.