scholarly journals DETERMINATION OF THE ACTUAL AREA OF DRY ACOUSTIC CONTACT IN THE SYSTEM “TRANSDUCER–PRODUCT” IN LOW-FREQUENCY DEFECTOSCOPY

2019 ◽  
pp. 5-15
Author(s):  
O. G. Bondarenko
Keyword(s):  
Piezoelectric Transducer ◽  
Low Frequency ◽  
Piezoelectric Transducers ◽  
Static Force ◽  
Pipe Surface ◽  
Directional Waves ◽  
Dry Contact ◽  
Acoustic Contact ◽  
Acoustic Antenna

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.

Determination of Damage to the Piezoelectric Sensor by Measuring the Electrical Capacitance

2015 ◽  
Vol 240 ◽  
pp. 31-35
Author(s):  
Witold Rządkowski ◽  
Paweł Pyrzanowski
Keyword(s):  
Cyclic Loading ◽  
Physical Properties ◽  
Strain Gauge ◽  
Piezoelectric Transducer ◽  
Strain Sensor ◽  
Piezoelectric Sensor ◽  
Load Level ◽  
Piezoelectric Transducers ◽  
Electrical Capacitance

This work presents testing mechanical defects of MFC piezoelectric transducers. The issue is important when piezoelectric transducer is used as eg. strain sensor. Repeatability of measurements is a goal, which can be obtained only if transducer has the same physical properties in every measurement. One way to determine damaged part of the sensor is measuring capacitance of MFC transducer. A couple of tests were performed to determine capacitance under non-destroying cyclic loading, and with loads causing PZT failure. Relation of capacity and load level was also investigated. All tests were validated with results from traditional resistive strain gauge

Low‐frequency piezoelectric‐transducer applications of ZnO film

1974 ◽  
Vol 25 (1) ◽  
pp. 10-11 ◽  
Author(s):  
Tadashi Shiosaki ◽  
Akira Kawabata
Keyword(s):  
Piezoelectric Transducer ◽  
Low Frequency ◽  
Zno Film

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

The low frequency motions of solvated Mn(ii) and Ni(ii) ions and their halide complexes

2014 ◽  
Vol 16 (45) ◽  
pp. 25101-25110 ◽  
Author(s):  
Vinay Sharma ◽  
Fabian Böhm ◽  
Gerhard Schwaab ◽  
Martina Havenith
Keyword(s):  
Low Frequency ◽  
Hydration Water ◽  
P Concentration ◽  
Halide Complexes ◽  
Absorption Measurements

Concentration dependent THz/FIR absorption measurements allow determination of individual solvated ion resonances and their influence on the hydration water spectrum.

Methyl Isocyanide: The Low-Frequency Bands ν8 and ν7, and a Determination of the Rotational Constant A0

1995 ◽  
Vol 173 (2) ◽  
pp. 423-430 ◽  
Author(s):  
J. Pliva ◽  
L.D. Le ◽  
J.W.C. Johns ◽  
Z. Lu ◽  
R.A. Bernheim
Keyword(s):  
Low Frequency ◽  
Rotational Constant ◽  
Frequency Bands ◽  
Methyl Isocyanide

Determination of Electric and Magnetic Properties of Commercial LTCC Soft Ferrite Material

2011 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Nelu Blaž ◽  
Andrea Marić ◽  
Goran Radosavljević ◽  
Nebojša Mitrović ◽  
Ibrahim Atassi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Low Frequency ◽  
Hysteresis Loops ◽  
Frequency Range ◽  
Dispersion Parameters ◽  
Simple Method ◽  
Component Design ◽  
Microwave Engineering ◽  
Characterization Procedure

This paper offers an effective, accurate, and simple method for permittivity and permeability determination of an LTCC (low temperature cofired ceramic) ferrite sample. The presented research can be of importance in the fields of ferrite component design and application, as well as for RF and microwave engineering. The characterization sample is a stack of LTCC tapes forming a toroid. Commercially available ferrite tape ESL 40012 was used and standard LTCC processing was applied for the sample fabrication. For the first time, the electrical properties of a ferrite toroid sample of ESL 40012 LTCC ferrite tape is presented at various frequencies. The electrical properties of LTCC ferrite materials, permittivity and specific resistivity, are shown in a frequency range from 10 kHz to 1 MHz using the capacitive method. The hysteresis properties of this material are also determined. B-H hysteresis loops were measured applying a maximum excitation of 2 kA/m and frequencies of 50 Hz, 500 Hz, and 1000 Hz. Permeability is determined in the frequency range from 10 kHz to 1 GHz and a characterization procedure is divided in two segments, for low and high frequencies. Low frequency measurements (from 10 kHz to 1 MHz) are performed using LCZ meter and discrete turns of wire, while a short coaxial sample holder and vector network analyzer were used for the higher frequency range (from 300 kHz to 1 GHz). In addition, another important factor required for the practical design of devices is presented, the temperature variation of the permeability dispersion parameters.

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