Vibration Diagnostic Methods Research Articles

Метод визначення вібраційних характеристик промислового обладнання в частотній та часовій областях

This paper proposes hardware and software solutions and a data processing method for vibration diagnostics of industrial equipment, which uses discrete Fourier transform and Allan dispersion to increase the accuracy and stability of measurement processes and result processing. The object of this study is the use of vibration diagnostic methods to implement the concept of maintenance of industrial equipment based on monitoring its current and future condition. The subject of this research is the hardware and software solutions for vibration diagnostics systems and methods for processing measurement results. The purpose of this work is to develop a new resource-saving IoT-oriented wireless solution for vibration diagnostics, where the contact method and MEMS accelerometers are used to measure vibration parameters and to evaluate the effectiveness of new methods and algorithms for processing experimental data. The task: justify the need to find new hardware and software solutions and methods of processing the obtained results for the implementation of the service concept based on the tracking of vibration indicators of technical equipment; provide basic hardware and software solutions for the implementation of the cloud platform of vibration diagnostics; develop methods of processing results; check the developed methods and algorithms using mathematical modeling methods and in an on-site experiment; compare the effectiveness of own and competitive solutions; draw conclusions and formulate a plan for further research. Conclusions. It has been proven that the combination of known analysis methods in the time and frequency domains with multi-level processing gives better results than analogous methods. The developed hardware and software tools and the method of processing measurement results effectively implement the contact method of vibration measurement, which provides the possibility of tracking the state of technical equipment. The developed equipment for the calibration of vibration acceleration sensors can reduce accelerometer errors. Further areas of research are the search for the optimal distribution of calculations on IoT levels, reducing the computational complexity of algorithms, increasing the time of continuous autonomous operation of the lower-level microcontroller, creating micro services for time-series analysis, and researching the dependence of the technical state of the equipment on the calculated Allan deviation.

Проблемы диагностики современных тепловозных двигателей

Objective: to consider the issue of diagnostics of modern diesel engines, in particular vibration diagnostics. Consider modern strategies and methods based on vibroacoustic signals that allow you to track and diagnose diesel engine malfunctions, as well as an assessment of the working process in the engine. To determine which means of measuring vibration parameters and methods of processing vibration signals can be considered the most reliable and informative. Propose to make adjustments to the currently used methods of processing vibration signals. Methods: comparison of the effectiveness of vibration measurement tools and mathematical methods of vibration signal processing. Results: the necessity of choosing mathematical methods of vibration signal processing is indicated, both for individual components of a diesel locomotive engine and for evaluating the workflow. Modern mathematical methods, applied to vibration diagnostics, require updating, due to an increase in computing power, as well as due to the development of powerful signal processing methods. To increase the reliability of the comparison results, it is necessary to take into account the large variability of the components and processes of the diesel engine. The need for additional study of modern mathematical methods of vibration signal processing is revealed. Practical importance: the necessity of introducing more modern methods of vibration signal processing is shown, which will optimize the durability of the components’ design using long operating cycles, reduce maintenance costs, track the service life of the internal combustion engine during the operation of the locomotive, improve the monitoring and diagnostics systems of the locomotive engine. The presented methods of assessing the use of certain methods of vibration diagnostics for diesel locomotives can be recommended for practical use.

Methods of determining internal damage in power transformers

Due to the variety of defects that arise in electrical machines, it is necessary to use more effective methods for monitoring their condition. All over the world research and development of new means and methods for monitoring powerful electrical machines during their operation is underway. Some examples of recent advances are vibration diagnostic methods for assessing the compaction of components inside a transformer, acoustic and electrical systems for monitoring partial discharges, data processing using digital methods, and new sensors for continuous monitoring of gases and moisture in oil, as well as hot spot temperatures. Additionally, thermal imaging testing of power equipment is also an important tool to ensure reliable operation. It is believed that the most effective method is gas chromatographic oil analysis, which can identify most defects in oil-filled equipment. During the operation of powerful electrical machines, the use of existing non-destructive testing methods does not allow a complete assessment of the condition of the main parts of the equipment, as an analysis of damage locations shows, 25% are damage to the core and windings. Effective monitoring of the condition and determination of the performance of transformers is of particular importance, since they are key elements in the operation of nuclear power plants. The paper considers the possibility of using the eddy current testing method; determining a defect in magnetic core steel is based on fixing the unevenness of the magnetic field on the horizontal or vertical planes of a yoke or rod consisting of electrical steel plates. Monitoring and evaluating the functioning of existing equipment, detecting deficiencies in the early stages of their development, when repair costs are still minimal, and preventing emergency failures become a priority. In accordance with the growth rate of detected deficiencies, monitoring is carried out from time to time or continuously, the maximum number of monitored characteristics is achieved when the transformer is fully tested to determine its functionality.

Диагностика электротехнических компонентов гидротехнического оборудования: эффективность комплексного подхода

Diagnostics of electrical components of hydrotechnical equipment used in agricultural production within the planned maintenance intervals with continuous analysis of residual resource is useful for reducing equipment operation costs. The use of inexpensive universal diagnostic equipment in conjunction with primary analysis of the state of units makes it possible to detect 60 to 80% of pre-failure states. To ensure efficient application of complex approach to primary diagnostics of electrical components of hydraulic equipment used in agricultural production, the authors considered the most common electric motors of pumping units, electrohydraulic distributors and switching equipment. Complex diagnostics included the use of a thermal imager, vibration signal processing systems and current signal control systems. The vibrograms of equipment control points were analyzed, the state of bearing units, cavitation characteristics of pumps were assessed by methods of acoustic and vibration diagnostics, hydraulic equipment leaks were searched, power cables breakdown zones were detected in accordance with methodical instructions for determining the breakdowns of power cables with voltage up to 10 kV RD34.20.516‑90. The article shows the possibilities of applying the diagnostics methodology based on surface thermograms to determine typical defects. Particularly discussed are the parameters of current signals from the electromagnet coils observed in case of distribution equipment malfunction. The authors give comparative evaluation of diagnostics methods with calculated efficiency determination. It is established that the method of combined diagnostics using the analysis of external thermal fields can halve the time of preliminary diagnostics of faults with a stable forecast of the failure time 2‑3 months before the critical state. This reduces the costs for detection of unit failures and simplifies the planning of maintenance procedures.

Analysis of the features of application of vibration diagnostic methods of induction motors of transportation infrastructure using mathematical modeling

1. Choudhary A, Goyal D, Shimi SL, et al. Condition Monitoring and Fault Diagnosis of Induction Motors: A Review. Arch Computat Methods Eng. 2019;26:1221-1238. https://doi.org/10.1007/s11831.... CrossRef Google Scholar

Применение методов преобразования Фурье и вейвлет-преобразования для вибродиагностики технического состояния тоннельных эскалаторов

To consider the possibility of improving the detection of early signs of escalator defects. To develop and improve methods for testing and functional diagnostics of escalators. To propose methods for digital signal processing. To develop an approach for correcting interpretation of signal processing results. The methods of vibration diagnostics and digital signal processing were used: including Fourier and wavelet transform. A comparison of Fourier and wavelet transform methods is presented. The possibility of their successful application for signal processing is shown. It was shown that the parameters of vibration diagnostic techniques and the methods of digital signal processing – Fourier transform and wavelet transform-require improvement. The reliability of calculation results can be increased by considering highly variable operational conditions of tunnel escalators. The need for additional examination of the technical condition of tunnel escalators is revealed. Fourier transform and wavelet analysis reveal changes in the nature of oscillations along the leads (an increase or a decrease in the energy level in the leads in phase and diametrically change places depending on the operation mode of the machine). This circumstance indicates the presence of gaps that are «selected» in a characteristic manner every time the direction of movement is changed. When there are any inhomogeneities in the material, wavelet transform analysis may provide the necessary information to determine the design defects, along with their location and possible defect type. The above considerations make the proposed methods of Fourier and wavelet transform of signals to be practically feasible.

Vibration based damage detection of bridge structures

The task of identifying damage to the load-bearing beams of large-span bridge structures using vibration diagnostic methods has been implemented, taking into account experimental uncertainties associated with natural phenomena and technological processes. The methodology for localizing damage is based on the analysis of dynamic characteristics of the structure, such as natural frequencies and modes of vibration. The study presents research on a finite element model of a bridge structure using a method for determining a damage indicator based on normalizing the values of vibration modes with respect to the values of vibration area.

МЕТОДЫ ИСКУССТВЕННОГО ИНТЕЛЛЕКТА В ДИАГНОСТИКЕ ОБОРУДОВАНИЯ ПРОКАТНОГО ПРОИЗВОДСТВА. ДИАГНОСТИКА ПОДШИПНИКОВ ИЗГИБО-РАСТЯЖНОЙ МАШИНЫ

This paper discusses the problem of diagnosing the condition of bearings in a tension leveler of a sheet mill. Due to aggressive conditions and location features, traditional vibration diagnostic methods are not applicable. The paper proposes an innovative solution based on a multizone temperature sensor. To build a model of the normal behavior of the system, a multivariate state estimation model and a neural network of the autoencoder structure were used. A comparison of the models’ performance is provided.

Highly sensitive methods for vibration diagnostics of fatigue damage in structural elements of aircraft gas turbine engines

Vibration diagnostics of damage belongs to the class of non-destructive methods, which usually do not take long time. However, the main problem of vibration diagnostics is relatively low sensitivity to the critical damage of fatigue crack type, which arises because of long time accumulation of plastic deformation. To improve the sensitivity and reliability of vibration diagnostics of damage two methods were considered. The first method was based on the fact, that a characteristic feature of vibrations of structural elements with fatigue crack is the occurrence of non-linear resonances (sub- and super-harmonic) and significant non-linearity of vibration response at these resonances. The second one – on the fact, that quite noticeable in certain cases increase of damping characteristic caused by a crack can be observed. Analytical and experimental studies of these methods were carried out as applied to the blades of aircraft gas turbine engines. As a result of the studies, the intensity of change in parameter of super-harmonic resonance and in damping characteristics at different parameters of crack was determined. Besides, the experimental techniques for vibration testing of turbine blades were developed. There was demonstrated, that the sensitivity of both considered methods of vibration diagnostics is several orders of magnitude higher than the sensitivity of conventional methods based on the change in natural frequencies and mode shapes, and they can be effectively used for the diagnostics of blades on the stage of engine repair.

СПЕКТРАЛЬНИЙ АНАЛІЗ СИГНАЛУ ВІБРАЦІЇ З ВИКОРИСТАННЯМ ПЕРЕТВОРЕННЯ ФУР’Є

The paper analyzes the topical issue of timely detection and prevention of a dangerous state of critical machines and mechanisms using vibration diagnostics as a promising method. It is proposed to use the method of analysis of vibration spectra in order to identify malfunctions, by processing the output signal from the sensor, which is sent to a personal computer, where a spectral analysis of the measured vibration signal is performed using a diagnostic program based on MATLAB. It is proposed to use spectral analysis, which is a traditional method of vibration diagnostics. It is supposed to determine the faulty state according to vibration measurement data and then to determine the nature of the fault according to the vibration signals analysis using the Fourier transform. It is proposed to process the output signal from the vibration sensor to a personal computer, where a spectral analysis of the measured vibration signal is carried out using a diagnostic program based on MATLAB. The use of FFT algorithms is due to a decrease in the number of operations performed, and, consequently, an increase in performance. It is shown that the decomposition of a complex signal in a Fourier series gives the components of the spectrum, which are, in narrow-band analysis, the harmonic components of the complex signal. It has been determined that narrowband spectral analysis allows detecting a larger number of faults or defects and is used for monitoring and in-depth diagnostics of equipment. Knowing the frequencies at which malfunctions of the kinematic pairs of machinery are manifested, the amplitude of the spectrum components can be used to assess their state. It was determined that spectral analysis is widely used in the processing of vibration diagnostics data, being the main and classical method of analysis. To optimize the duration of the test, it is necessary to take into account the relationship between the spectrum bandwidth and the signal accumulation time. The pass-through characteristic reflects the dependence of the signal level on time at a certain frequency, illustrating the process of signal accumulation during narrow-band spectral analysis. The narrower the analysis strip, the longer the measurements take.

Анализ методов вибродиагностики металлических конструкций

Due to the constant machine complexity increasing as well as the requirements imposed on them, the issue of ensuring their reliability is becoming more and more urgent. The main part of any machine is supporting metal structure, which state determines the state of the machine as a whole. This determines the need to diagnose structures in order to prevent failures. At present, the methods of vibration diagnostics are being widely developed, as applied to objects of various industries. Scientists’ research is aimed at studying various types of defects, vibration parameters, methods for detecting defects and assessing the residual life. The article considers the main current trends in the development of vibration diagnostics methods. The sensitivity of the dynamic structure characteristics to the presence of a defect in the form of a crack has been investigated. A finite element analysis of a steel I-beam was performed for various cases of its fixation and crack location. The dependence of the natural frequencies and amplitude-frequency characteristics of the beam on the crack size has been analyzed. It is found that the presence of a defect has the greatest effect on the frequency response of the beam.

VIBRATION DIAGNOSTICS OF FATIFUE DAMAGE IN STRUCTURAL ELEMENTS OF GAS TURBINE ENGINES AT THE REPAIR STAGE

Vibration diagnostics of damage belongs to the class of non-destructive methods, which usually do not take long time. However, the main problem of vibration diagnostics is relatively low sensitivity to the critical damage of fatigue crack type, which arises because of long time accumulation of plastic deformation. To improve the sensitivity and reliability of vibration diagnostics of damage two methods were considered. First method was based on the fact, that a characteristic feature of vibrations of structural elements with fatigue crack is the occurrence of non-linear resonances (sub- and super-harmonic) and significant non-linearity of vibration response at these resonances. Secon one – on the fact, that quite noticeable in certain cases increase of damping characteristic caused by a crack can be observed. Analytical and experimental studies of these methods were carried out as applied to the blades of aircraft gas turbine engines. As a result of the studies, the intensity of change in parameter of super-harmonic resonance and in damping characteristics at different parameters of crack was determined. Besides, the experimental techniques for vibration testing of turbine blades were developed. There was demonstrated, that the sensitivity of both considered methods of vibration diagnostics is several orders of magnitude higher than the sensitivity of conventional methods based on the change in natural frequencies and mode shapes, and they can be effectively used for the diagnostics of blades on the stage of engine repair. All the other conditions being equal, second-order superharmonic resonance demonstrates a higher sensitivity to the presence of cracks than the damping characteristic. The smallest crack with an area of 0.2% considered in the work causes a reliably recorded non-linearity of vibration response at superharmonic resonance of order of 2/1. At this the change of damping characteristic slightly exceeds the error of experiment.

Method of vibration diagnostics of the technical condition of electronic equipment structures

The article considers the method of vibration diagnostics of onboard electronic devices based on the analysis of resonant frequencies. An algorithm for diagnosing mechanical defects of the studied blocks and nodes is presented. The structure of the complex of software tools for diagnostics automation and the results of testing the proposed method are presented. The main goal of the research is to improve the accuracy of identification of design defects of on-Board electronic devices. The transition from the analysis of the frequency response to the resonant frequencies that characterize the physical and mechanical parameters of the structure is due to greater stability and lower measurement error of this characteristic. To achieve this goal, a diagnostic model of the method has been developed that allows taking into account the spread of parameters of the electronic tool, both for the serviceable state and for the state with a defect. To estimate the permissible deviations of resonant frequencies from the nominal values, statistical simulation was performed using the Monte Carlo method. It was also possible to increase the reliability of the results of the physical experiment by determining the best position of the accelerometer in terms of the response received. The article provides a structure and description of the algorithm for searching for it. The results of approbation of the considered method on the example of the printed node of the voltage divider of the control unit of the aircraft are presented. In CAD SolidWorks, the serviceable state of the test node was modeled, for which four resonant frequencies were determined, and the state with a defect in the form of a detachment of the attachment. Analysis of the results showed a shift of three values of resonant frequencies relative to the correct state. The conducted series of 10 tests revealed the defect in all 10 cases (with the permissible error of the research result). This indicates a high degree of reliability of the data obtained, the adequacy of the diagnostic model of the method and the correctness of the applied algorithms.

Research of the characteristics of acoustic processes using wavelet transformation for detecting a diagnostic sign of the technical state of gas pumping units

The object of research is the degradation processes that take place in gas-pumping units (GPU) during its long-term operation and lead to the appearance of defects and, as a result, to a change in its technical state. Today, methods of parametric and vibration diagnostics are used to determine the technical condition of the GPU. To identify diagnostic signs of the technical state of the GPU, various transformations are used, in particular the wavelet transforms used in vibration processing that accompany the operation of the GPU and their technological parameters. At the same time, in the study of the diagnostic signs of the technical state of the GPU, the acoustic processes accompanying the operation of the GPU, which can be more informative in comparison with the vibration ones, were practically not considered. The developed experimental research methodology and their technical support made it possible to record the acoustic processes accompanying the operation of the gas compressor unit type GTK-25-i of the Nuovo Pignon company (Italy). In the course of the experimental studies, the realizations of the acoustic processes of the GPU were obtained for its three states – «nominal», «defective» and «current». Further studies of acoustic processes for three states of the GPU type GTK-25-i and using the wavelet transform showed that by the appearance of the wavelet spectrograms it is difficult to notice the difference in the appearance or disappearance of various frequency components depending on the technical state of the GPU. To obtain quantitative indicators of this dependence, a discrete wavelet transform was carried out, which makes it possible to identify characteristic trends in the change in noise values at different scales. The values of the approximation norm and the detail norms in relation to the signal norm (in percent) were obtained for a five-level wavelet decomposition with datasets. A linear dependence of the norm of the wavelet-component of the fifth-order detailing on the operating time of GPU type GTK-25-i and (changes in the technical state), which can be taken as a diagnostic sign of its technical state, has been established. The investigated diagnostic feature can be used as the basis for the method of diagnosing the technical state of GPU type GTK-25-i based on the characteristics of its acoustic process using the wavelet transform. An approach to identifying a diagnostic sign of the technical state of a GPU type GTK-25-i is considered based on the characteristics of acoustic processes using a wavelet transform can be used to identify a diagnostic sign of a condition for any type of GPU.

Integrated Diagnostic Method Analysis of Use in the Inspection of Rolling Mills

Organizing maintenance of equipment in accordance with its technical condition is a way to reduce production costs in the metallurgical industry. Equipment condition assessment is possible by various methods, but one of the most promising is the method of monitoring the thermal fields of devices. The method of monitoring the equipment temperature fields is not new and is often used for diagnostics of metallurgical equipment. This article analyzes the economic efficiency of the applied method in comparison with the method of vibration diagnostics, control current signal, a method of condition monitoring of hydraulic fluids. The authors describe their experience in equipment diagnostics.

Operational Effectiveness of Phase-Chronometric and Neurodiagnostic Methods for Controlling Rolling-Element Bearing Degradation

In the present study, problems associated with monitoring the condition of rolling-element bearings (REBs) – one of the most common technical devices of rotor units in machines and mechanisms – are considered. A novel approach to metrological support and assessment of the technical condition of rolling-element bearings during operation is presented. Existing approaches are analyzed, including methods of vibration diagnostics, envelope analysis, wavelet analysis, and others. The application of the phase-chronometric and neurodiagnostic methods for monitoring a bearing over its life cycle is considered. For this purpose, a unified format of measurement information was used. The possibility of providing REB diagnostics on the basis of measurement information obtained from the shaft and the cage is evaluated.

Vibration-based fault diagnosis of the natural gas compressor using adaptive stochastic resonance realized by Generative Adversarial Networks

The compressor as an important energy transmission equipment is widely used in the natural gas pipelines to pressurize natural gas, which is prone to fail due to the characteristics of high pressure, flammability and corrosion of the natural gas. The faulty compressors may cause natural gas leakage, transmission interruption, and even explosion. Vibration monitoring and fault diagnosis of the natural gas compressor is an effective technology to ensure its security. Due to the strong noise interference, the traditional vibration diagnostic methods are difficult to obtain better effects. Stochastic resonance (SR) is a useful technology that can make full use of the noise components contained in the vibration signals to enhance the weak fault features to complete fault diagnosis. However, the applications of SR in fault diagnosis are faced with many problems, such as the difficulty of parameter selection and the need for intensive data. To solve them, an adaptive generation model of SR parameters is established by using Generative Adversarial Networks (GAN), an adaptive SR-GAN method is accordingly proposed for completing the fault diagnosis of a natural gas compressor. The simulation experiment and field data analysis are adopted to verify the effectiveness of the proposed method. The results indicate that the proposed method can improve diagnostic accuracy by 2.07% compared to the traditional adaptive SR method realized by multilayer perceptron neural network, and improve the signal-to-noise ratio by 2.25 dB at most compared with the other three methods. Moreover, the proposed method still has higher accuracy under the condition of small sample sizes. The proposed method can expand the sample when the sample size is smaller, so that the model can contain completely the operating conditions to improve the accuracy of fault diagnosis. It provides a new idea for the vibration monitoring of natural gas compressors.

New methods for geoinformation systems of tests and analysis of causes of failure elements of pumping stations

The large pumping stations (PS) planned for reconstruction in our republic in terms of consumption, power-to-weight ratio, and controls are the largest in the world: failure of them even for a small period of time can lead to enormous damage. Therefore, the formulation and solution of theoretical problems in the operation of these facilities, taking into account the reliability indicators, is an extremely important national economic task. Until now, the design of the National Assembly, including large ones, has been conducted without taking into account the quantitative index of reliability. The value of reliability has long been underestimated, and error correction required significant costs. Currently, increasing the efficiency of the operation of pumping stations is associated with the development of energy-saving and resource-saving technologies. Diagnostics is one of the modern and perfect ways to determine the main malfunctions that occur in pumping units. The main goal of diagnosing the technical condition of pumping units is to preliminarily identify the occurring malfunctions in it and ensure durability, reliability, reliability, and operational efficiency. The article presents the effect of vibration on pumping units and analysis of methods of vibration diagnostics, information is given on the possibility and advantages of devices for continuous vibration diagnostics.

Electromagnetic Method for Determining the Internal Resistance of Conductive Materials

The electromagnetic method of vibration diagnostics of rod conductive parts is theoretically described. Natural frequencies of the transverse oscillations of the rod are determined for various boundary conditions. In theory, method of experimental determination of internal friction coefficient of electrically conductive materials is developed.

Efficiency of application of the phase-chronometric method and neurodiagnostics for monitoring the degradation of rolling bearings during operation

The paper presents an alternative approach to metrological support and assessment of the technical condition of rolling bearings in operation. The analysis of existing approaches, including methods of vibration diagnostics, envelope analysis, wavelet analysis, etc. Considers the possibility of applying a phase-chronometric method for support on the basis of neurodiagnostics bearing life cycle on the basis of the unified format of measurement information. The possibility of diagnosing a rolling bearing when analyzing measurement information from the shaft and separator was evaluated.