scholarly journals Using Hilbert Transform in Diagnostic of Composite Materials by Impedance Method

2020 ◽  
Vol 64 (4) ◽  
pp. 334-342 ◽  
Author(s):  
Volodymyr Eremenko ◽  
Artur Zaporozhets ◽  
Vitalii Babak ◽  
Volodymyr Isaienko ◽  
Kateryna Babikova
Keyword(s):  
Composite Materials ◽  
Nondestructive Testing ◽  
Hilbert Transform ◽  
Instantaneous Frequency ◽  
Information Quality ◽  
Low Frequency ◽  
Mechanical Impedance ◽  
Phase Characteristic ◽  
Impedance Method ◽  
Materials Testing

The article is devoted to the problem of the increasing of information quality for the impedance method of nondestructive testing. The purpose of this article is to get for the pulsed impedance method of nondestructive testing the additional informative parameters. Instantaneous values of the information signal's amplitude is a sensitive parameter to the effects of interference, in particular friction, which necessitates the use of additional informative features. It was experimentally measured signals from defective and defectless areas of the test pattern. Using of the Hilbert transform gave possibility to determine phase characteristics of these signals and realize demodulation to extract a low-frequency envelope for further analysis of its shape. It was received the informative features as a result of researches. Among them are instantaneous frequency of a signal, the integral of a phase characteristic on the selected interval and the integral of a difference signal phase characteristics. In order to compare quality of the defect detection using selected parameters it was carried out evaluation of the testing result reliability for a product fragment made of a composite material. Considering the influence of the change in the mechanical impedance of the researched area on the phase-frequency characteristics of the output signal of the converter, it is proposed to use as the diagnostic signs: the instantaneous frequency and the value of the phase characteristic of the current signal for certain points in time. The proposed informative features enable to increase general reliability of composite materials testing by the pulsed impedance method.

scholarly journals ACOUSTIC NON-DESTRUCTIVE TESTING OF MULTILAYERED STRUCTURES FROM PCM DURING THE PRODUCTION AND OPERATION OF AVIATION TECHNIQUE

2019 ◽  
pp. 36-49
Author(s):  
A. M. Slyadnev
Keyword(s):  
Composite Materials ◽  
Frequency Control ◽  
Low Frequency ◽  
Flaw Detector ◽  
Impedance Method ◽  
Multilayer Structures ◽  
Destructive Testing ◽  
Multilayered Structures ◽  
Effective Use ◽  
Production And Operation

Considered the use in the production of aviation equipment (airplanes and helicopters), polymer composites differing in enhanced operational and technological properties, such as strength, rigidity, level of working temperatures, etc. Examples are given of using newer gliders in multilayer structures MS-21 aircraft and Mi-38 helicopter of modern composite materials. The review of defects of multilayer structures made of polymer composite materials arising at the stage of manufacturing, storage, transportation and operation of aircraft, and low-frequency methods of their control is presented. It is noted that the main of low-frequency control methods are the impedance method and the method of free oscillations proposed by domestic scientists.The principle of operation of the first portable multifunctional computerized pulsed flaw detector DAMI-C09, combining impedance, impact and eddy current ND methods, is described. It is noted that the flaw detector can be used for manual and automated, as part of a robotic complex, to identify bundles, nonglues and other violations of the integrity of composites, honeycomb structures and glued structures, to determine corrosion centers, surface and internal defects in non-ferromagnetic materials. A feature of the flaw detector is the simplified preparation process for work due to the automated mode of tuning the signal in amplitude or phase using a spectrum analyzer, documenting the monitoring results with the ability to transfer to a computer and subsequent processing with the help of a special APM of the Flaw Detector. Examples of the effective use of the flaw detector in the production and operation of aviation equipment are given.

ANALYTIC SAMPLING APPROXIMATION BY PROJECTION OPERATOR WITH APPLICATION IN DECOMPOSITION OF INSTANTANEOUS FREQUENCY

2013 ◽  
Vol 11 (05) ◽  
pp. 1350040 ◽  
Author(s):  
YOUFA LI ◽  
TAO QIAN
Keyword(s):  
Hardy Space ◽  
Numerical Experiment ◽  
Hilbert Transform ◽  
Mild Condition ◽  
Instantaneous Frequency ◽  
Projection Operator ◽  
Approximation Scheme ◽  
Special Functions ◽  
Cauchy Kernel ◽  
Sequence Of Functions

A sequence of special functions in Hardy space [Formula: see text] are constructed from Cauchy kernel on unit disk 𝔻. Applying projection operator of the sequence of functions leads to an analytic sampling approximation to f, any given function in [Formula: see text]. That is, f can be approximated by its analytic samples in 𝔻s. Under a mild condition, f is approximated exponentially by its analytic samples. By the analytic sampling approximation, a signal in [Formula: see text] can be approximately decomposed into components of positive instantaneous frequency. Using circular Hilbert transform, we apply the approximation scheme in [Formula: see text] to Ls(𝕋2) such that a signal in Ls(𝕋2) can be approximated by its analytic samples on ℂs. A numerical experiment is carried out to illustrate our results.

Specific Features of Nondestructive Testing of Polymer and Composite Materials Using Air-Coupled Ultrasonic Excitation and Laser Vibrometry

2021 ◽  
Vol 57 (8) ◽  
pp. 647-655
Author(s):  
V. Yu. Shpil’noi ◽  
V. P. Vavilov ◽  
D. A. Derusova ◽  
N. V. Druzhinin ◽  
A. Yu. Yamanovskaya
Keyword(s):  
Composite Materials ◽  
Nondestructive Testing ◽  
Laser Vibrometry
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