Low-frequency ultrasonic Bessel-like collimated beam generation from radial           modes of piezoelectric transducers

The conditions for the emission of acoustic energy into the pipeline environment and the reception of reflected signals from inconsistencies in dry acoustic contact cause certain dimensions of the actual contact area between the transducers and the pipe surface. The basic approaches to the determination of the actual area of dry acoustic contact between the surfaces of the piezoelectric transducer and the pipe are formulated under the influence of constant static force of pressing the surfaces in low-frequency flaw detection using ultrasonic directional waves. Expressions have been proposed to determine the area of actual acoustic contact for single and numerical micro projections of the pipe surface. The principle of quality control of balancing of acoustic antenna piezoelectric transducers in modern systems of low-frequency diagnostics of the technical state of longitudinal pipelines by ultrasonic directed waves is described. It is revealed that after correct balancing of all the acoustic antenna piezoelectric transducers, the column image does not appear on the display screen and the mathematical support of the system will automatically collect the technical status of the diagnosed section of the pipeline, the results of which are displayed on the display screen. It is established that the actual area of dry acoustic contact in the "piezoelectric product" system in low-frequency defectoscopy depends on the magnitude of the static force of pressing the surface of the piezoelectric transducer to the surface of the product. It is revealed that the deformation of the micro protrusions of the surface of the product under the action of static clamping force is uneven, which does not allow to fully calculate the actual area of dry contact by mathematical methods. It is shown that in modern systems of low-frequency ultrasonic diagnostics of extended pipelines, directional waves control the quality of dry contact of the surface of the piezoelectric transducer with the surface of the pipe by balancing acoustic antennas with the use of special test programs.

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Broad-band acoustic low frequency collimated beam for ultrasonic imaging

The Journal of the Acoustical Society of America ◽

10.1121/1.4806008 ◽

2013 ◽

Vol 133 (5) ◽

pp. 3423-3423

Author(s):

Cristian Pantea ◽

Dipen N. Sinha

Keyword(s):

Broad Band ◽

Ultrasonic Imaging ◽

Low Frequency ◽

Collimated Beam

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Resonance-enhanced compact nonlinear acoustic source of low frequency collimated beam for imaging applications in highly attenuating media

The Journal of the Acoustical Society of America ◽

10.1121/1.4970084 ◽

2016 ◽

Vol 140 (4) ◽

pp. 3204-3204

Author(s):

Cristian Pantea ◽

Dipen N. Sinha

Keyword(s):

Low Frequency ◽

Acoustic Source ◽

Nonlinear Acoustic ◽

Collimated Beam

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High Frequency Performance of Piezoelectric Diaphragms for Impedance-Based SHM Applications

Engineering Proceedings ◽

10.3390/ecsa-7-08185 ◽

2020 ◽

Vol 2 (1) ◽

pp. 16

Author(s):

Guilherme Rezende ◽

Fabricio Baptista

Keyword(s):

High Frequency ◽

Structural Damage ◽

Low Cost ◽

Low Frequency ◽

Experimental Tests ◽

Piezoelectric Transducers ◽

Low Frequencies ◽

High Frequencies ◽

Electromechanical Impedance ◽

Damage Indices

Piezoelectric transducers are used in a wide variety of applications, including damage detection in structural health monitoring (SHM) applications. Among the various methods for detecting structural damage, the electromechanical impedance (EMI) method is one of the most investigated in recent years. In this method, the transducer is typically excited with low frequency signals up to 500 kHz. However, recent studies have indicated the use of higher frequencies, usually above 1 MHz, for the detection of some types of damage and the monitoring of some structures’ characteristics that are not possible at low frequencies. Therefore, this study investigates the performance of low-cost piezoelectric diaphragms excited with high frequency signals for SHM applications based on the EMI method. Piezoelectric diaphragms have recently been reported in the literature as alternative transducers for the EMI method and, therefore, investigating the performance of these transducers at high frequencies is a relevant subject. Experimental tests were carried out with piezoelectric diaphragms attached to two aluminum bars, obtaining the impedance signatures from diaphragms excited with low and high frequency signals. The analysis was performed using the real part of the impedance signatures and two basic damage indices, one based on the Euclidean norm and the other on the correlation coefficient. The experimental results indicate that piezoelectric diaphragms are usable for the detection of structural damage at high frequencies, although the sensitivity decreases.

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An Approach for Compensation of Geometric Faults in Machine Tools

Volume 6: 5th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B, and C ◽

10.1115/detc2005-84241 ◽

2005 ◽

Cited By ~ 2

Author(s):

Christian Rudolf ◽

Jo¨rg Wauer ◽

Christian Munzinger ◽

Ju¨rgen Fleischer

Keyword(s):

Machine Tools ◽

Multibody System ◽

Equations Of Motion ◽

Dynamical Behavior ◽

Low Frequency ◽

Piezoelectric Transducers ◽

Preliminary Design ◽

Flexible Multibody System ◽

Parallel Kinematics

Geometric faults in parts of machine tools with parallel kinematics lead to stresses in the structure and deflections of the tool center point, reducing the quality of the workpiece. Improving the design of machine tools can reduce these influences. In this paper an approach to compensate the influence of geometric faults in parallel kinematics based on the design of an adaptronic strut is introduced. The strut is divided in two halves and two piezoelectric transducers are implemented in between them, used as sensor and actuator, respectively. A preliminary design of the adaptronic strut is presented. The problems of measuring low-frequency signals using piezoelectric transducers are considered in the design. Finally, a primary analytical model of the dynamical behavior of the adaptronic compensation unit is presented. The strut and its connection to the surroundings are regarded as a flexible multibody system, the equations of motion are derived using linear graph theory. Some simulation results are presented.

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