Embedded Self-Sensing Piezoelectric Active Sensors for On-Line Structural Identification

2001 ◽  
Vol 124 (1) ◽  
pp. 116-125 ◽  
Author(s):  
Victor Giurgiutiu ◽  
Andrei N. Zagrai
Keyword(s):  
Mechanical Response ◽  
Impedance Spectrum ◽  
Structural Identification ◽  
Calibration Procedure ◽  
Structural Vibration ◽  
Sensor Calibration ◽  
Ultrasonic Frequency ◽  
Active Sensors ◽  
Turbine Engine ◽  
On Line

The benefits and limitations of using embedded piezoelectric active sensors for structural identification at ultrasonic frequency are highlighted. An analytical model based on structural vibration theory and theory of piezoelectricity was developed and used to predict the electro-mechanical (E/M) impedance response, as it would be measured at the piezoelectric active sensor’s terminals. The model considers one-dimension structures and accounts for both axial and flexural vibrations. Experiments were conducted on simple specimens in support of the theoretical investigation, and on realistic turbine blade specimen to illustrate the method’s potential. It was shown that E/M impedance spectrum recorded by the piezoelectric active sensor accurately represents the mechanical response of a structure. It was further proved that the response of the structure is not modified by the presence of the sensor, thus validating the latter’s noninvasive characteristics. It is shown that such sensors, of negligible mass, can be permanently applied to the structure creating a nonintrusive sensor array adequate for on-line automatic structural identification and health monitoring. The sensor calibration procedure is outlined. Numerical estimation of the noninvasive properties of the proposed active sensors in comparison with conventional sensors is presented. Self-diagnostics capabilities of the proposed sensors were also investigated and methods for automatic self-test implementation are discussed. The paper underlines that the use of piezoelectric wafer active sensors is not only advantageous, but, in certain situations, may be the sole investigative option, as in the case of precision machinery, small but critical turbine-engine parts, and computer industry components.

scholarly journals Characterization of Piezoelectric Wafer Active Sensors

2000 ◽  
Vol 11 (12) ◽  
pp. 959-976 ◽  
Author(s):  
Victor Giurgiutiu ◽  
Andrei N. Zagrai
Keyword(s):  
Mechanical Response ◽  
Impedance Spectrum ◽  
Calibration Procedure ◽  
Structural Vibration ◽  
Sensor Calibration ◽  
Active Sensors ◽  
One Dimensional ◽  
Active Sensor ◽  
Aluminum Plates ◽  
In The Beginning

In the beginning, the classical one-dimensional analysis of piezoelectric active sensors is reviewed. The complete derivation for a free-free sensor is then extended to cover the cases of clamped and elastically constrained sensors. An analytical model based on structural vibration theory and theory of piezoelectricity was developed and used to predict the electromechanical (E/M) impedance response, as it would be measured at the piezoelectric active sensor’s terminals. The model considers one-dimensional structures and accounts for both axial and flexural vibrations. The numerical analysis was performed and supported by experimental results. Experiments were conducted on simple beam specimens to support the theoretical investigation, and on thin gauge aluminum plates to illustrate the method’s potential. It was shown that E/M impedance spectrum recorded by the piezoelectric active sensor accurately represents the mechanical response of a structure. It was further proved that the response of the structure is not modified by the presence of the sensor, thus validating the sensor’s non-invasive characteristics. The sensor calibration procedure is outlined and statistical analysis was presented. It was found that PZT active sensors have stable and repeatable characteristics not only in as-received condition, but also while mounted on 1-D or 2-D host structure. It is shown that such sensors, of negligible mass, can be permanently applied to the structure creating a non-intrusive sensor array adequate for on-line automatic structural identification and health monitoring.

scholarly journals A Nonintrusive Rotor Blade Vibration Monitoring System

1996 ◽  
Author(s):  
Henry Jones
Keyword(s):  
Rotor Blade ◽  
Rotating Machinery ◽  
Vibration Monitoring ◽  
Static Deflection ◽  
Blade Vibration ◽  
Turbine Engine ◽  
Measurement Systems ◽  
Timing Data ◽  
On Line ◽  
Engine Rotor

A technique for measuring turbine engine rotor blade vibrations has been developed as an alternative to conventional strain-gage measurement systems. Light probes are mounted on the periphery of the engine rotor casing to sense the precise blade passing times of each blade in the row. The timing data are processed on-line to identify (1) individual blade vibration amplitudes and frequencies, (2) interblade phases, (3) system modal definitions, and (4) blade static deflection. This technique has been effectively applied to both turbine engine rotors and plant rotating machinery.

Structural Health Monitoring With Piezoelectric Active Sensors

2000 ◽  
Author(s):  
Howard A. Winston ◽  
Fanping Sun ◽  
Balkrishna S. Annigeri
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Damage ◽  
Electromechanical Coupling ◽  
Low Cost ◽  
Piezoelectric Element ◽  
Impedance Spectrum ◽  
Active Sensors ◽  
Electromechanical Impedance ◽  
Structural Health

A technology for non-intrusive real-time structural health monitoring using piezoelectric active sensors is presented. The approach is based on monitoring variations of the coupled electromechanical impedance of piezoelectric patches bonded to metallic structures in high-frequency bands. In each of these applications, a single piezoelectric element is used as both an actuator and a sensor. The resulting electromechanical coupling makes the frequency-dependent electric impedance spectrum of the PZT sensor a good mapping of the underlying structure’s acoustic signature. Moreover, incipient structural damage can be indicated by deviations of this signature from its original baseline pattern. Unique features of this technology include its high sensitivity to structural damage, non-intrusiveness to the host structure, and low cost of implementation. These features have potential for enabling on-board damage monitoring of critical or inaccessible aerospace structures and components, such as aircraft wing joints, and both internal and external jet engine components. Several exploratory applications will be discussed.

Uncertainty Evaluation on Multi-Hole Aerodynamic Pressure Probes

2020 ◽  
Author(s):  
Andrea Notaristefano ◽  
Paolo Gaetani ◽  
Vincenzo Dossena ◽  
Alberto Fusetti
Keyword(s):  
Uncertainty Analysis ◽  
Evaluation Method ◽  
Experimental Testing ◽  
Uncertainty Propagation ◽  
Calibration Procedure ◽  
Fast Response ◽  
Uncertainty Evaluation ◽  
Sensor Calibration ◽  
Pressure Probe ◽  
Aerodynamic Pressure

Abstract In the frame of a continuous improvement of the performance and accuracy in the experimental testing of turbomachines, the uncertainty analysis on measurements instrumentation and techniques is of paramount importance. For this reason, since the beginning of the experimental activities at the Laboratory of Fluid Machines (LFM) located at Politecnico di Milano (Italy), this issue has been addressed and different methodologies have been applied. This paper proposes a comparison of the results collected applying two methods for the measurement uncertainty quantification to two different aerodynamic pressure probes: sensor calibration, aerodynamic calibration and probe application are considered. The first uncertainty evaluation method is the so called “Uncertainty Propagation” method (UPM); the second is based on the “Monte Carlo” method (MCM). Two miniaturized pressure probes have been selected for this investigation: a pneumatic 5-hole probe and a spherical fast response aerodynamic pressure probe (sFRAPP), the latter applied as a virtual 4-hole probe. Since the sFRAPP is equipped with two miniaturized pressure transducers installed inside the probe head, a specific calibration procedure and a dedicated uncertainty analysis are required.

Mechanical effects of vasoactive drugs on carotid sinus

1986 ◽  
Vol 250 (6) ◽  
pp. R1074-R1080 ◽  
Author(s):  
L. B. Bell ◽  
J. L. Seagard ◽  
E. J. Zuperku ◽  
J. P. Kampine
Keyword(s):  
Carotid Sinus ◽  
Calibration Procedure ◽  
Drug Infusion ◽  
Vasoactive Agents ◽  
Vessel Segment ◽  
Pressure Axis ◽  
Before And After ◽  
Anesthetized Dogs ◽  
On Line ◽  
Vasodilator Drug

Carotid sinus diameter (CSD) is influenced by changes in sympathetic tone and vasoactive agents. This study was designed to determine which mechanical properties of the carotid sinus region were influenced by infusing vasoconstrictors (epinephrine, 4.56 X 10(-6) M, and phenylephrine, 9.85 X 10(-5) M) and a vasodilator (nitroprusside, 1.68 X 10(-4) M). CSD, carotid sinus length (CSL), pressure (CSP), and compliance (CSC), and arterial pressure were all recorded simultaneously from the isolated constant-flow-perfused carotid sinus region of 11 anesthetized dogs (35 mg/kg pentobarbital sodium) before and after drug perfusion. CSC was measured by a method previously described in which 13 microliters of perfusate is injected into the segment in a step-like manner and the resultant step change in pressure recorded. The compliance of the vessel segment is read on-line after a calibration procedure. CSD and CSL were measured using sonomicrometer length gauges positioned across and along the length of the carotid sinus segment. At a CSP of 99.9 +/- 0.6 (SE) mmHg, CSD, CSL, and CSC were 8.50 +/- 0.44 mm, 9.44 +/- 0.84 mm, and 0.46 +/- 0.05 microliter/mmHg, respectively. Decreasing CSP to 50 mmHg significantly reduced CSD and CSL and increased CSC. Increasing CSP to 150 mmHg produced opposite results. Vasoconstrictor drug infusion significantly decreased and vasodilator drug infusion significantly increased both CSD and CSL, producing parallel shifts in the CSP-CSD and -CSL curves toward and away from the pressure axis. The shift to new pressure-volume curves resulted in no change in CSC in response to the vasoactive agents.

Adaptive-passive structural vibration attenuation using distributed absorbers

2002 ◽  
Vol 216 (3) ◽  
pp. 223-235 ◽  
Author(s):  
N Jalili ◽  
E Esmailzadeh
Keyword(s):  
Vibration Suppression ◽  
Sufficient Conditions ◽  
Structural Vibration ◽  
Dynamic Vibration Absorber ◽  
Vibration Attenuation ◽  
Adaptive Capability ◽  
On Line ◽  
Lumped Masses ◽  
Necessary And Sufficient ◽  
Tuning Strategy

A distributed dynamic vibration absorber with adaptive capability is presented to improve vibration suppression characteristics of harmonically excited structures. A double-ended cantilever beam carrying intermediate lumped masses forms the absorber subsection. The adaptive capability is achieved through concurrent adjustment of the positions of the moving masses, along the beam, to comply with the desired optimal performance. The necessary and sufficient conditions for the existence of periodic oscillatory behaviour, along with some physical bounds placed on the absorber parameters, form a constrained optimization problem for the optimum tuning strategy. Through numerical simulations it is shown that adaptive tuning is achieved by the variation of tuning mass locations such that the first-mode natural frequency is modulated on-line. The optimally tuned absorber provides considerable vibration suppression improvement over the passive and detuned absorbers.

Investigations of Flutter and Aerodynamic Damping of a Turbine Blade: Experimental Characterization

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Charles E. Seeley ◽  
Christian Wakelam ◽  
Xuefeng Zhang ◽  
Douglas Hofer ◽  
Wei-Min Ren
Keyword(s):  
Mechanical Response ◽  
Numerical Models ◽  
Structural Vibration ◽  
Aerodynamic Damping ◽  
Actuation System ◽  
Electromagnetic Actuation System ◽  
Wide Range ◽  
Large Motion ◽  
Damping Effects ◽  
Numerical Approaches

Flutter is a self-excited and self-sustained aero-elastic instability, caused by the positive feedback between structural vibration and aerodynamic forces. A two-passage linear turbine cascade was designed, built, and tested to better understand the phenomena and collect data to validate numerical models. The cascade featured a center airfoil that had its pitch axis as a degree-of-freedom to enable coupling between the air flow and mechanical response in a controlled manner. The airfoil was designed to be excited about its pitch axis using an electromagnetic actuation system over a range of frequencies and amplitudes. The excitation force was measured with load cells, and the airfoil motion was measured with accelerometers. Extraordinary effort was taken to minimize the mechanical damping so that the damping effects of the airflow over the airfoil, that were of primary interest, would be observable. Assembling the cascade required specialized alignment procedures due to the tight clearances and large motion. The aerodynamic damping effects were determined by observing changes in the mechanical frequency response of the system. Detailed aerodynamic and mechanical measurements were conducted within a wide range of Mach numbers (Ma) from Ma = 0.10 to 1.20. Experimental results indicated that the aerodynamic damping increased from Ma = 0.10 to 0.65, dropped suddenly, and was then constant from Ma = 0.80 to 1.20. A flutter condition was identified in the interval between Ma = 0.65 and Ma = 0.80. The aerodynamic damping was also found to be independent of displacement amplitude within the tested range, giving credence to linear numerical approaches.

A Real-Time and On-Line Visual System for Seamless Steel Pipe Linearity Measurement

2005 ◽  
Vol 295-296 ◽  
pp. 393-398
Author(s):  
C.J. Liu ◽  
Xue You Yang ◽  
Ji Gui Zhu ◽  
S.H. Ye
Keyword(s):  
Coordinate System ◽  
Real Time ◽  
Local Coordinate System ◽  
Steel Pipe ◽  
Sensor Calibration ◽  
Steel Pipes ◽  
Global Calibration ◽  
On Line ◽  
Linearity Error ◽  
Seamless Steel

Linearity is a very important parameter for seamless steel pipes. A real-time and on-line visual measurement system for seamless steel pipe linearity is presented. The system consists of several structured-light visual sensors. Each sensor can achieve the coordinate of the center of partial steel pipe in its local coordinate system. Through global calibration, all coordinates measured can be transformed into an integrated coordinate system. The linearity error of steel pipe can be assessed. This method can fulfill 100% on-line and real-time linearity measurement. A pair structure-light sensor is designed to improve accuracy and a suspension-wires method for sensor calibration and global calibration is used. Through experiments, it shows that the method not only meets the need of precise calibration but also significantly improves the efficiency and feasibility.

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