The model of acoustic emission signal formation during friction and wearing of surfaces of composite materials was examined. The forms of acoustic emission resultant signals were shown. The regularities of parameter change in acoustic emission resultant signals with an increasing rotation speed were determined according to the results of modeling. It was found that theoretical and experimental results of acoustic emission signals registered during friction of composite material surface layers agree well.

The paper considers the results of modelling acoustic emission signals that form under variations in the rotational speed of a friction pair made of a composite material. It is found that the energy accumulation in acoustic emission signals that form relative to time takes place in accordance with linear law under normal wear of a friction pair. If the rotational speed of a friction pair increases, the rates of accumulated average energy and accumulated total energy of the acoustic emission signals that form also grow. The resulting acoustic emission signals have both accumulated average energy and accumulated total energy. A comparison of these two types of energy is conducted. It is shown that the application of data averaging reduces the rate of the accumulated energy of the acoustic emission signals that form.

Подано результати моделювання акустичного випромінювання зі зростанням осьового навантаження на пару тертя з композиційного матеріалу. Показано, що збільшення осьового навантаження приводить до зростання амплітудних та енергетичних параметрів результуючих сигналів акустичної емісії. Визначено залежності процентного приросту амплітудних та енергетичних параметрів результуючих сигналів акустичної емісії. Описано, що зі збільшенням осьового навантаження на пару тертя підвищення середнього рівня амплітуди випереджає зростання його стандартного відхилення та дисперсії. Розглянуто найбільш чутливі параметри до зростання осьового навантаження на пару тертя – дисперсія середнього рівня енергії результуючих сигналів акустичної емісії

The simulation of the fracture process of elements of the composite material under the action of shear force and the formation of acoustic emission signals, taking into account changes in the geometric size of the elements of the composite material was conducted. The results of theoretical studies shows that changes in the geometric size of CM elements affects on the development process of its destruction, and formed AE signal. An increase in the geometric size of CM elements at constant loading conditions, led to decrease in the speed of its destruction. Thus there is a decrease in the amplitude of AE signals, increasing the duration of their leading edge and duration. Was established that an increase in the geometric size of elements of the CM led to reduction of the maximum amplitude, power, energy, and area under the curve of formed AE signals by the linear laws. Such change in the maximum amplitude and duration of formed AE signals, obviously due to the fact that an increase in the geometric size of CM elements decreases the speed of their destruction. Reducing energy and power formed AE signals, probably due to a decrease in the maximum amplitude of formed AE signals by increasing the geometric size of CM elements, which is preceded by an increase in their duration.

Some models of the formation of acoustic emission signals by the destruction of composite material by shear load were examined. We have formulated a mathematical description of the quantity of elements that remains in the process of composite destruction and mathematical description of acoustic emission signals. The regularity of changes in acoustic emission signals for a simple model of composite destruction and for a model that takes into account the process of the destruction of the elements of composite material was shown.

Acoustic emission signals in non-coherent addition of waves and coherent addition of displacement were analysed. It is shown that for non-coherent addition of waves the area under a curve of a temporary course of acoustic emission intensity does not depend on the entry speed of the load. For an acoustic emission, which is calculated by addition of displacement impulses, the area under a curve of change of effective amplitude in time does not depend on the entry speed of the load. Santrauka Atlikta akustinės emisijos signalų analizė, kai bangų sumavimas yra nekoherentinis, o poslinkių sumavimas – koherentinis. Parodyta, kad plotas žemiau kreivės, rodančios akustinės emisijos intensyvumo kitimą laikui bėgant, nepriklauso nuo apkrovos įvedimo greičio, kai bangų sumavimas nekoherentinis. Akustinėje emisijoje, kuri apskaičiuojama sumuojant impulsų poslinkį, plotas žemiau kreivės, rodančios efektyvios amplitudės kitimą bėgant laikui, nepriklauso nuo apkrovos įvedimo greičio.

A model of acoustic emission signal formation at the prevailing mechanism of the destruction of composite materials is considered. The results of acoustic emission signal modelling are presented, taking into account the variable velocity of loading change. Acoustic emission signal experimental research results corresponding to theoretical research results are considered in this paper. It is shown that irregularity of the trailing edge of the acoustic emission signal is influenced by the change in the rate of the destruction process in composites. Santrauka Išnagrinetas akustines emisijos signalo modelis su vyraujančiu kompozitiniu medžiagu irimo mechanizmu. Pateikti akustines emisijos signalu modeliavimo rezultatai, ivertinant skirtinga apkrovos pasikeitimo greiti. Taip pat pateikti eksperimentinio akustines emisijos signalu tyrimo rezultatai, kurie sutampa su teoriniais tyrimais. Parodyta, kad akustines emisijos signalo galinio fronto netolygumas atsiranda tuomet, kai kinta kompozitines medžiagos irimo greitis.

Описано руйнування композиційного матеріалу і формованого сигналу акустичної емісії залежно від виду руйнування волокон. Отримано залежності зміни осьового напруження, кількості волокон, що залишилися, і формованих сигналів акустичної емісії. Проведено аналіз закономірностей їх зміни.

The analysis of AE signals is executed, mouldable at destruction of composition material under the action of loading of change. Description of processes is conducted is model and simplest. It is considered, how resilient properties of standard change depending on the enclosed loading, and also it is rotined that the change of axial tension on fibres takes a place at their destruction as a result of achievement of the critical loadings of stretching and bending. This tension changes continuously. However at the beginning of process of destruction this tension can have breaking or continue to grow, but with less speed. At such character of change of dependence of axial tension in time to define (to fix) beginning of process of destruction of fibres of standard possibly only subject to the condition implementation of complete cycle of loading. It is rotined that the AE signals arise (begin to be formed) up directly in the point of beginning of destruction of standard, regardless of type of destruction of fibres (stretch or bend). Registration of AE signals in the process of loading of composite material can be executed for control of achievement of the maximum possible loadings, beginning which irreversible destruction of composite. It is marked, that the AE signals, which are registered at the tests of composite materials have pain composition forms which differ from considered, are real. It is conditioned, foremost, by the simplest description of the presented models which foresee gradual slow enough destruction of fibres. In addition, at description of acoustic radiation it is necessary to take into account more difficult character of redistribution of tensions in composite material, and also kinetics of process of destruction.

The modeling of composite material fracture and formed of acoustic emission signal is conducted depending onthe geometrical size of fibers. Basic conformities to the law of change acoustic emission signal parameters areshowed.

The results of experimental researches of influencing a sampling interval of acceleration and speed oscillation signals on amplitude-frequency relations of displacement signals after using the operations of double or unary transformation are reviewed. Are shown the main regularity a change of displacement signals output amplitudes from frequency of input signals at set values of a sampling interval. Is determined, that the sampling interval does not influence on amplitude-frequency displacement signals relations under condition, that the transformation is executed from time constants, which value is peer to half part of period a input oscillation signals of speed and acceleration.

The results of experimental researches of influencing a sampling interval of registered acceleration and speed oscillation signals on amplitudes the signals of speed and displacement, after fulfillment the conversions operations are reviewed. Are shown the main regularity a change of signals speed and displacement output amplitudes from time of conversion at given sampling intervals. Is determined, that the sampling interval does not influence to change a maximum amplitudes of converted signals provided that the conversion implements from time constants, that value is peer to which one to half part of period a speed and acceleration oscillations input signals.

The obtained data of the resulting acoustic signals emission at the prevailing mechanism of the material surface layer wear under friction have been considered. It has been shown that the form and parameters of the acoustic emission resulting signals depend on the time of the initiation of type-I or type-II secondary structures fracture (rotation velocity of friction pair), as well as the stressed-deformed state of the materials’ surface layers of friction pairs.

The challenge of pilot training include adapting to an industry in which the environment is formed by steep upturns and downturns, cut‐throat competition, and advanced technology that continues to change the role of the pilot and in which safety always must match the continuously increasing demands of efficiency. The pilot training performed at flight training organisations (FTOs) is the fundament in the education of captains and first officers who will be able to manage the operational “sharp end” of this environment. Santrauka Pateikti laiko konstantos įtakos greitėjimo signalų arba virpesių greičio signalų virtimo poslinkio signalu tyrimo rezultatai. Nustatyti poslinkio signalo amplitudės pasikeitimo dėsningumai po greitėjimo ir greičio signalų pasikeitimo. Parodyta, kad poslinkio signalo amplitudės pasikeitimo klaida priklauso nuo pasikeitimo laiko konstantos nustatytam įeinančio signalo dažniui. Šiuo atveju jo minimali reikšmė atitinka pasikeitimo laiko konstantos reikšmę, kuri yra lygi pusei įeinančio signalo periodo. Pateikti poslinkių matavimo rezultatai, naudojant virpesių greičio daviklius bei jų palyginimo su duomenimis, kurie buvo gauti etaloniniu poslinkių davikliu, rezultatai. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: diagnostika, vibracija, signalų spektras, greitėjimo signalas, greičio signalas, pasikeitimo signalas, dinaminis poslinkis.

In the paper is reviewed the methods and means, which used at technical diagnostic of bridge designs. The general approaches to technical diagnostic, the main methods, primary converters and hardwares, which used on static and dynamic tests of bridge designs are reviewed.