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1

New method for bearing fault diagnosis based on VMD technique

Bousseloub Yahia, Medjani Farida, Benmassoud Ahmed, Kezai Taher, Belhamra Ali, Attoui Issam

Diagnostyka

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2024

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Vol. 25, No. 2

art. no. 2024208

EN

Variational Mode Decomposition (VMD) is a useful tool for decomposing complex multi-component signals. However, one major drawback of VMD is the need to accurately determine the value of sub-signals (IMFs) before starting the process of segmentation. In fact, achieving optimal reconstruction of the denoised original signals depends on the determining optimal number of IMFs (K). This requirement poses a challenge in the capability of analyzing non-stationary or noisy signals. In this paper, a new approach to optimize the variational mode decomposition technique is proposed. This approach automatically estimates the optimal K and also effectively detects the characteristic frequencies associated with faulty bearings. This method is a combination of two algorithms which are based on cross-correlation and root mean square (RMS) statistical analysis. To confirm the efficacy of the proposed method, the bearing vibration dataset from the Case School of Engineering are used. Then, the K obtained through the proposed method are compared with other methods. The results demonstrate that the proposed approach exhibits superior robustness and precision when autonomously evaluating the optimal K for effective identification of bearing fault.

2

Analysis of development tendencies of metrological technologies to control rangefinders of an electronic distance measurement instruments

Burachek Vsevolod, Khomushko Dmytro, Tereshchuk Oleksiy, Kryachok Sergíy, Belenok Vadim

Advances in Geodesy and Geoinformation

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2022

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Vol. 71, no. 1

art. no. e13, 2022

EN

The article analyses the development of metrological control technologies for electronic distance measurement rangefinders to determine their main characteristic of accuracy – the root mean square error of distance measurement. It is established that the current reference linear bases are reliable and serve as the main means of transmitting a unit of length from the standards to the working means of measuring length. The article describes the existing linear reference bases and specifies their accuracy and disadvantages. It is concluded that the disadvantages of linear reference bases are deprived of the reference linear bases built in special laboratories. They use distances measured by the differential method with laser interferometers as reference distances. The application of such technology allowed to automate the processes of measurements and calculations. There is development of fibre-optic linear bases, in which optical fibres of known length are used as model lines. The article offers a new technical solution – a combination of fiber-optic and interference linear bases, which allows to qualitatively improve the system of metrological support of laser rangefinders. This is achieved by having a fiber-optic unit, which allows you to create baselines of increased length, while ensuring small dimensions of the baseline, and relative interference base, which provides high accuracy of linear measurements and does not require calibration of the base with a precision rangefinder, which eliminates several difficulties associated with changes in the refractive index, makes measurements independent of the wavelength of the radiation source and almost independent of the ambient temperature.

3

Influence of Semi-Active Suspension Characteristics on the Driving Comfort

Pečeliūnas Robertas

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 1

18--25

EN

The article analyzes the influence of modern-day vehicle suspension characteristics on the passenger’s comfort sensation. The cars with air suspension were selected for the experiments and the suspension was equipped with mode selection options – “Comfort” and “Sport” . A sinusoidal manoeuvre was ensured with a steering wheel rotation robot. The experimental tests were carried out by changing car suspension modes and wheel sizes. The experiments and data processing were carried out in accordance with the provisions of the ISO 2631–1 international standard. In the experimental test, the longitudinal and lateral acceleration projections captured by the sensor and roll rate of the vehicle were set to provide the most comfortable adjustment of the car suspension mode. After filtering the measured vertical acceleration values, the comfort sensation was expressed as the root mean square (RMS) of vibration acceleration value. After evaluating the passenger’s sense of comfort, a summary of the effect of the car suspension-driving mode was provided.

4

Vibration diagnostic of a friction process in slide bearings

Lepiarczyk D., Gawędzki W.

Tribologia

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2018

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nr 2

73--80

EN

An analysis of the condition of technical objects is carried out by diagnostic systems, the purpose of which is to detect irregularities in their operation and to prevent damages. In slide bearings, it applies to the diagnostic of friction and thermal phenomena of mating friction pairs. Among many methods of bearing diagnostics, special attention should be paid to vibration diagnostic methods based on measurements of relative vibration parameters or on absolute vibration (displacement, velocity, or acceleration of vibration). Methods of the vibration diagnostic of bearings rely on periodic or continuous measurements of relative vibration parameters of the bearing housing in relation to the rotor (in the case of slide bearings the measurements of the bearing sleeve in relation to the shaft neck) or absolute vibration parameters of the bearing housing (i.e. the sleeve in the case of slide bearing). The article presents a method of vibration diagnostics of friction phenomena that occur during the operation of slide bearings under various lubrication and load conditions. There are presented methods of analysis and the interpretation of measurement data obtained as a result of the conducted slide bearing tests on the laboratory stand. A method for assessing a technical condition of the slide bearing friction pairs is proposed.

PL

Rozpoznanie stanu obiektów technicznych jest realizowane przez systemy diagnostyczne, których celem jest wykrywanie nieprawidłowości w ich działaniu i zapobieganiu uszkodzeniom. W łożyskach ślizgowych dotyczy to diagnostyki zjawisk tarciowych i cieplnych współpracujących węzłów tarcia. Wśród wielu metod diagnostyki łożysk na szczególną uwagę zasługują metody diagnostyki drganiowej, bazujące na pomiarach parametrów drgań względnych bądź drgań bezwzględnych (przemieszczenie, prędkość lub przyspieszenie drgań). Metody diagnostyki drganiowej stanu technicznego łożysk polegają na okresowych lub ciągłych pomiarach parametrów drgań względnych obudowy łożyska względem wirnika (w przypadku łożysk ślizgowych panewki łożyska względem czopa wału) bądź parametrów drgań bezwzględnych obudowy łożyska (czyli panewki w przypadku łożyska ślizgowego). W artykule przedstawiono metodę diagnostyki drganiowej zjawisk tarciowych, jakie zachodzą podczas pracy łożysk ślizgowych przy różnych warunkach smarowania i obciążenia. Przedstawiono metody analizy i interpretacji wyników pomiarów otrzymanych w wyniku przeprowadzonych badań łożyska ślizgowego na stanowisku laboratoryjnym. Zaproponowano metodę oceny stanu technicznego węzła tarcia łożyska ślizgowego.

5

Drilling projects by tool condition monitoring system (TCMS)

Garc´Ia-Sanz-Calcedo J., Salgado D. R., Gonzalez A. G.

Engineering Transactions

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2016

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Vol. 64, iss. 4

555--561

EN

In this paper, an online tool condition monitoring system (TCMS) for drilling is presented. The method is based on monitoring the spindle and feed motor currents. Root mean square (RMS) values of the spindle and feed motor currents, drill diameter, spindle speed and feed rate are the inputs to the network, and drill wear is the output. Drilling experiments were carried out over a wide range of cutting conditions to map the relationship between the input information and a tool wear. The performance and the architecture of the neural network have been validated with experiments, and a good agreement in an estimation of the tool condition was found. The results show that this method can be effectively used to verify and determine the tool wear.

6

Comparison of sensitivity coefficients for joint angle trajectory between normal and pathological gait

Błażkiewicz M., Wit A

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 1

83-91

EN

Gait recordings exhibit intra-subject, inter-subject, within-trial and between-trial variability as well as data analysis methods. In medicine, comparison of different measuring method results or quantifying changes due to specific treatment is required. The aim of this study was to compare a group homogeneity with respect to dispersion around the reference curve and to compare waveforms of normal and pathological gait data based on joint angle curves. Data files were tracked using APAS system. Our own model of lower limb was used to calculate the trajectories of joint angles for 5 groups: healthy men, women, children, persons with drop foot and Trendelenburg's sign. Waveform parameterizations, RMS, IAE and correlation coefficients were used to compare joint angles with reference curve. The sample scores obtained in this work provide an important information about closeness in the shape of two curves. Using multiple techniques of data analysis will benefit and give more accurate information.

7

Wpływ obcięcia słowa akumulatora fazy oraz skończonej rozdzielczości przetwornika C/A na wartość skuteczną sygnału generowanego przez bezpośredni syntezer częstotliwości (DBS)

Popek G., Kampik M., Musioł K.

Prace Naukowe Politechniki Śląskiej. Elektryka

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2010

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z. 4

29-37

PL

W pracy przeanaiizowano wpływ obcięcia słowa akumulatora fazy oraz skończonej rozdzielczości przetwornika C/A na wartość skuteczną sygnału generowanego przez bezpośredni syntezer częstotliwości (DDS). Zaproponowano model matematyczny, pozwalający na wyznaczenie zakresu przestrąjania układu DDS oraz oszacowania jego parametrów, tzn. długości słowa akumulatora fazy, maksymalnego obcięcia słowa akumulatora fazy, tak aby parametry te miały wpływ na wartość skuteczną generowanego sygnału mniejszy od założonej wielkości.

EN

The paper presents influence of phase word truncation effect and finite resolution of DAC on signal's root mean square value, which is generated by Direct Digital Synthesizer (DDS). Proposed mathematical model allows to set the frequency range and parameters of DDS i.e. number of bits in phase word to achieve RMS error smaller than some assumed value.

8

Wykorzystanie wartości skutecznej sygnału emisji akustycznej oraz metod sztucznej inteligencji do oceny zużycia ściernicy

Sutowski P.

Pomiary Automatyka Kontrola

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2009

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R. 55, nr 4

255-258

PL

W pracy przedstawiono propozycję oceny zużycia ściernic metodą pośrednią, opartą na analizie wartości skutecznej sygnału emisji akustycznej. Umiejętność podejmowania decyzji jest jednym z elementów wyróżniających inteligentne działanie, dlatego budowa systemu diagnostyki, który charakteryzowałby się takimi właściwościami wymaga użycia odpowiedniego narzędzia wykonawczego. Włączenie w układ monitorujący teorii zbiorów rozmytych, pozwoliło dokonać oszacowania stopnia stępienia czynnej powierzchni ściernicy i oceny jej okresu trwałości w trakcie procesu szlifowania.

EN

In the paper the indirect method of grinding wheel wear evaluation is presented. This method is based on analysis of the root-mean-square value of an acoustic emission signal (AE). Application of the acoustic emission signal as a measure of changes occurring in the grinding zone enables the indirect assessment of the process without its stopping. The ability to take a decision is one of the elements distinguishing intelligent activities. Design of a diagnostic system with such kind of abilities requires the use of an appropriate executive tool. The conditional attributes for an intelligent expert system were set basing on the analysis of the test results, and in particular on the grinding process output values. For individual attributes there were assumed appropriate limit values representing a sharp, average or strongly used grinding wheel not suitable for further work. As a criterion of wear there were assumed macro- and micro-changes in the active surface of the grinding wheel as well as the stress in te top layer of the workpiece. The methods of artificial intelligence were implemented in the system to ensure its correct operation. Fuzzy logic included in the monitoring system allowed estimating the degree of the grinding wheel active surface wear and its lifetime during flat surface grinding. The complete system of the grinding wheel wear control which takes into account the temporary cutting ability and the chosen quality criterion is just a conceptional solution. It is expected that this system can successfully be used for construction of monitoring units and control of machining process.

9

An investigation of the grinding wheel wear with the use of root-mean-square value of acoustic emission

Sutowski P., Plichta S.

Archives of Civil and Mechanical Engineering

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2006

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Vol. 6, no 1

87-98

EN

This paper presents the results of an investigation of the grinding wheel wear in a peripheral surface grinding process. During this investigation varying geometrical parameters of an active grinding wheel surface have been measured and the components of the grinding force and acoustic emission signal have been recorded. On the basis of these output quantities an analysis has been conducted of an acoustic emission descriptor's practicability, i.e. a root-mean-square (RMS) value, to characterize the cutting abilities of a grinding wheel in the time progress of its work. This article also presents a new energy coefficient, which determines the rate of grinding wheel wear in the form of a RMS value of acoustic emission signal falling on a contact surface of a grinding wheel. Moreover, the article presents some examples of a correlation between the root-mean-square value of acoustic emission signal can be a useful tool to monitor the surface roughness during the grinding process.

PL

Przedstawiono wyniki badań nad zużyciem ściernicy elektrokorundowej w procesie obwodowego szlifowania płaszczyzn. Mierzono zmieniające się parametry geometryczne czynnej powierzchni ściernicy (CPS), rejestrowano wartości składowych siły szlifowania oraz sygnał emisji akustycznej. Na podstawie tych wielkości wyjściowych procesu przeanalizowano przydatność deskryptora emisji akustycznej (EA), jakim jest wartość skuteczna (RMS), w scharakteryzowaniu zdolności skrawnych ściernicy w miarę czasu jej pracy. Zaprezentowano także nowy współczynnik energetyczny, określający stopień zużycia ściernicy, w postaci wartości skutecznej sygnału emisji akustycznej przypadającej na powierzchnie kontaktu ściernicy. Ponadto przedstawiono przykłady korelacji wartości skutecznej sygnału emisji akustycznej z chropowatościa powierzchni szlifowanego przedmiotu, które wskazują na możliwość wykorzystania sygnału EA i jej wartości skutecznej (RMS) do monitorowania chropowatości powierzchni szlifowanej.

10

Zastosowanie wstępnego przetwarzania RMS w badanich komfortu w pojazdach

Strachowski P., Wyrębkiewicz A.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

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2002

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Z. 76

261-267

PL

W artykule zaproponowano uproszczenie metody pomiaru drgań działających na organizm ludzki. Przedstawiono trudności w wykonywaniu oceny widmowej wg PN-91/S-04100. Następnie opisano realizację oraz zalety wstępnego przetwarzania przebiegów przyspieszeń oddziałujących na kierowcę. Ponadto przedstawiono prototypowy układ wstępnego przetwarzania sygnału przyspieszenia w RMS.

EN

In the paper was presented proposition of new method in whole body vibrations measurement. Authors have compared research that are including in polish standard PN-91/S-04100 and research with RMS converter. Next they have described prototype of acceleration to RMS converter unit.

11

Identification of steam-water two-phase flow regimes in vertical upward tube

Bai B., Guo L., Zhao L.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

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1999

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Z. 67

173--183

EN

Both the fluctuating static pressures on the tube wall and the differential pressure fluctuation were measured to obtain the objective identification of steam-water two-phase flow regimes in a vertical upward tube of 20.0-mm interior diameter. The test pressures were 1.0MPa, 2.0MPa and 3.0MPa and the mass flux ranged from 100 to 900kg/m2s. The fluctuating mechanisms were studied by the statistical theory. The root mean square (RMS) of the pressure fluctuation can not be used to discriminate the flow regime transition under the condition of the high pressure, which was used successfully by Wambsganss in air-liquid loop. The frequency of differential pressure fluctuation ranged from 0 to 5 Hertz, and the shapes of the PDF and PSD concerned the various flow regimes. The flow regimes can be identified based on the RMS of the differential pressure fluctuation. The results by the method agreed well with the flow regimes provided by McQuillan and Whalley.