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1

Digital Twins for Metallic Additive Manufacturing in Marine Engineering

Pavlenko Petro

Polish Maritime Research

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2026

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nr 3

112--123

EN

The aim of this study was to explore the potential of using digital twins to enhance the accuracy and reliability of additive manufacturing under marine operating conditions. A comprehensive theoretical and analytical framework was developed for creating a digital twin for wire arc additive manufacturing (WAAM) in marine engineering, in which external destabilising factors were taken into account. It was found that without digital control, under conditions involving vibrations (0.2–3 Hz), temperature differentials of up to 500°C and platform instability, the risk of defect formation was increased. The numerical values reported here were derived from modelling results, a review of the literature, and analytical generalisation of published WAAM and digital twin data, rather than from new full-scale offshore experiments. The use of digital twins can enable real-time monitoring of parameters such as the wire feed speed (2–10 mm/s), arc power (300–1200 W), and feed angle (20–45°), thus allowing the heat transfer to be optimised and residual stresses to be reduced. Modelling-based synthesis and analytical generalisation of published data show that the implementation of this framework reduces the number of defective zones from 18 to four per component, decreases the energy consumption per part from 6.2 to 4.1 kWh, and improves the dimensional repeatability from ±0.9 to ±0.25 mm. Digital twins also allow the printing trajectory to be adapted to current conditions through integrated sensors and deformation modelling, thereby ensuring operational reliability on offshore platforms. The use of digital twins is therefore critically important for improving the accuracy, energy efficiency, and operational reliability of WAAM in marine environments.

2

Practical implementation of self-balancing method for a washing machine

Majewski Tadeusz, Ładyżyńska-Kozdraś Edyta, Bajkowski Jerzy, Meraz Melo Marco, Ahearn Gale A.

Advances in Science and Technology. Research Journal

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2026

|

Vol. 20, no. 3

1--17

EN

This article presents the properties of a front-load washing machine equipped with a self-balancing system and its possibility of industrial application in a series of productions. The dynamic model describes the behavior of the unbalanced drum and the free elements during balancing. The article defines the vibratory forces responsible for changing the position of the free elements concerning the drum which leads to the self-balancing phenomena. The kinetic-static model with the vibratory forces is compared with the solution of a set of differential equations. Because the difference between them is small, such a model is used for further analysis. The parameters of a real washing machine have some deviations that influence its work. Various analyses present their impact on decreasing the method's efficiency. Each of them is studied to establish the residual unbalance generated. Finally, the authors propose a procedure to establish acceptable maximum deviations for the parameters of the washing machine to obtain the required level of balancing.

3

Experimental tests and analytical model for stick-slip phenomenon reduction with the use of longitudinal tangential vibrations

Leus Mariusz, Rybkiewicz Marta, Gutowski Paweł

Advances in Science and Technology. Research Journal

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2026

|

Vol. 20, no. 3

74--86

EN

The article presents the results of experimental investigations and simulation analyses regarding the potential for partial reduction or complete elimination of the stick-slip phenomenon in sliding motion through the introduction of forced tangential longitudinal vibrations into the contact zone of the friction pair, with precisely defined parameters such as amplitude and frequency. An original analytical model is presented, enabling the selection of optimal parameters of the forced vibrations, under which the stick-slip phenomenon for a given friction pair can be reduced or completely eliminated. The investigations were carried out for three friction pairs comprising C45 steel, GGG40 cast iron, and polytetrafluoroethylene (PTFE), characterized by distinctly different mechanical properties. A very good agreement was obtained between the results of experimental tests and model analyses, demonstrating accurate modeling of frictional phenomena in the contact zone of the friction pair during sliding motion using the adopted computational algorithm.

4

Effect of the B stiffness submatrix on the free oscillation of thin-walled plates made of a general laminate

Kolakowski Jerzy, Teter Andrzej

Advances in Science and Technology. Research Journal

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2026

|

Vol. 20, no. 8

420--429

EN

This study investigates natural frequencies of simply supported thin-walled rectangular plates made of laminates with arbitrary stacking sequences. A detailed analysis is made of laminates whose stacking sequences meet the non-zero condition for coupling stiffness submatrix B components. Twelve laminate stacking sequences exhibiting different types of in-plane and out-plane coupling effects are selected, assuming that the plies are of the same thickness. A comparison is made between the effects of selected components of the coupling stiffness submatrix B and inertial force components on the natural frequencies of the rectangular laminate plates under consideration. Classical laminate plate theory (CLPT) is used in the considerations. Obtained solutions of the eigenproblems for the cases of unloaded rectangular plates made of a general laminate show that the correct determination of eigenvalues requires a detailed analysis of all B stiffness matrix components and beam model reduction factors.

5

Selected structural and material challenges of pumped-storage hydro power plants in Poland and worldwide

Dudziak Sławomir, Kozyra Zofia, Zbiciak Artur, Bartman Marcin

Materiały Budowlane

|

2025

|

nr 12

186--191

EN

This paper presents selected design and material challenges associated with the construction and operation of pumped‑storage power plants in Poland and worldwide. The plant’s operating environment is not fully controllable due to water contamination in the reservoirs and its aggressiveness, particularly towards the concrete in the supporting structure. Another challenge is vibration, which is caused by operating mechanical equipment and the dynamic action of water during pumping and discharge. Despite numerous technical challenges, pumped-storage power plants remain a key component of the power system, supporting grid stability and the development of renewable energy sources.

PL

W artykule przedstawiono wybrane wyzwania konstrukcyjne i materiałowe dotyczące budowy i eksploatacji elektrowni szczytowo-pompowych w Polsce i na świecie. Środowisko pracy elektrowni nie jest w pełni możliwe do kontroli ze względu na zanieczyszczenia wody w zbiornikach i jej stopnia agresywności zwłaszcza w przypadku betonu w konstrukcji wsporczej. Kolejnym wyzwaniem są drgania, których źródłem są pracujące urządzenia mechaniczne oraz dynamiczne działanie wody w trybie pompowania, jak i zrzutu wody. Pomimo wielu wyzwań technicznych, elektrownie szczytowo-pompowe pozostają kluczowym elementem systemu energetycznego, wspierając stabilność sieci i rozwój odnawialnych źródeł energii.

6

Ograniczanie hałasu silników trakcyjnych – projekt i analiza wibroakustyczna

Król Emil

Materials Science and Welding Technologies / Technologie Materiałowe i Spawalnicze

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2025

|

Vol. 69, No. 2

48--54

PL

W artykule przedstawiono proces projektowania nowego silnika trakcyjnego z magnesami trwałymi typu SMwsK280M16B, opracowanego w Łukasiewicz – Górnośląskim Instytucie Technologicznym. Silnik o mocy maksymalnej 650 kW i momencie maksymalnym 5900 Nm zaprojektowano z uwzględnieniem wysokiej sprawności, zwartej konstrukcji oraz minimalizacji emisji hałasu. Równolegle przeprowadzono analizy elektromagnetyczne i wibroakustyczne, umożliwiające ocenę wpływu zmian konstrukcyjnych na hałas i drgania. Wyniki obliczeń potwierdziły brak rezonansów w krytycznych zakresach prędkości obrotowych oraz spełnienie wymagań akustycznych. Prace zrealizowano z wykorzystaniem zintegrowanego podejścia obejmującego symulacje numeryczne, analizę modalną oraz badania prototypów.

EN

This article presents the design process of a new permanent magnet traction motor, type SMwsK280M16B, developed at the Łukasiewicz – GIT Institute. The motor, with a peak power of 650 kW and a maximum torque of 5900 Nm, was designed with a focus on high efficiency, compact construction, and minimized noise emission. In parallel, electromagnetic and vibroacoustic analyses were conducted to assess the impact of design modifications on noise and vibration levels. The simulation results confirmed the absence of resonances within critical speed ranges and compliance with acoustic requirements. The work was carried out using an integrated approach that included numerical simulations, modal analysis, and prototype testing.

7

Research on the energy recovery system in the active horizontal seat suspension of a working machine

Jereczek Bartosz, Maciejewski Igor, Błażejewski Andrzej, Pecolt Sebastian, Krzyżyński Tomasz

Journal of Theoretical and Applied Mechanics

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2025

|

Vol. 63 nr 4

809--814

EN

This paper investigates the potential for longitudinal vibration energy recovery in a seat suspension system through the implementation of a brushless direct current (BLDC) motor. The work focuses on two states of system operation. The first one is when an electric motor works as an actuator in the powering mode to withstand horizontal forces. The second one occurs in the regenerative mode when the kinetic energy of the system is partially converted into electricity. Within the scope of the presented study, the efficiency of the energy regeneration process under random vibration conditions of different intensities is investigated experimentally. Measurement results are presented in the form of vibration transmittance functions for a suspension with energy regeneration compared to a conventional passive and fully active system.

8

Development of a dynamic vibration absorber in the form of a variable inertia pendulum

Loch Piotr, Bugajewski Karol, Przybyłowicz Piotr, Chiliński Bogumił

Journal of Applied Mathematics and Computational Mechanics

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2025

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Vol. 24, nr 4

37--50

EN

Nowadays, to maximize space utilization, multi-story buildings are designed to occupy as little surface area as possible. However, the high slenderness of these struc tures makes them susceptible to forces caused by factors such as wind and tectonic plate movements. Prolonged exposure to vibrations reduces the building’s lifespan and leads to its degradation. To minimize the impact of vibrations while maintaining slenderness and relatively low structural rigidity, a solution in the form of a dynamic vibration absorber can be applied. Structures already use absorbers in the form of pendulums, as seen in the Taipei 101 skyscraper, for example. The subject of study is an absorber in the form of a pendulum with a variable moment of inertia, achieved by extending the cable, which allows the structure to adapt to current forces. This significantly reduces the time of exposure to harmful influences. A skyscraper model with a variable-length pendulum was developed and analyzed through simulations, confirming the hypothesis of a significant reduction in exposure.

9

Semi-Active Control of Energy Transfer Between Vibration Modes in Mechanical Structures

Ostrowski Mariusz

IPPT Reports on Fundamental Technological Research

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2025

|

nr 2

1--231

EN

This thesis is devoted to a new semi-active modal control methodology of frame structures. The control allows for precise transfer of the mechanical energy between structural vibration modes. It is realised by the lockable joints connecting structural beams. These joints can be dynamically locked and work as rigid connections, transmitting the bending moments between the adjacent beams, or can be unlocked and work as hinges. The locking effect introduces modal coupling that results in energy exchange between the vibration modes. The proposed control methodology has two potential applications: attenuation of low-frequency vibration and enhancement of the energy harvesting process. In the former application, the vibration energy is transferred into the high-frequency vibration modes and then effectively dissipated due to the higher damping coefficients of these modes. In the latter possible application, the energy harvester is attached to the controlled structure. Then, the energy is transferred from the currently excited structural vibration modes into the preselected one that cooperates well with the energy harvester in terms of installation location and natural frequency. This research is motivated by the fact that existing semi-active control strategies aimed at inducing energy transfer are heuristic in nature and typically capable of transferring energy only towards higher vibration frequencies. They do not employ any feedback from the state expressed in terms of modal parameters. Furthermore, any knowledge about the influence of the locking effect on modal coupling and modal energy transfer is very limited. An additional motivation for the research is the recent effort devoted to improve the balance between peak efficiency and operational frequency bandwidth of energy harvesters by introducing intentional nonlinearities, studying internal resonance phenomena and designing adaptive devices. Investigation of the locking effect focuses on the fact that locking and unlocking joints changes the dynamic properties of the structure, effective number of structural degrees of freedom, modal basis and its dimension. It is shown that the highest-dimension modal basis that is obtained for all joints in the unlocked state can be adopted for investigation of the structural behaviour even if joints become locked. Then, the modal coupling effect is included for proper description of the structural behaviour. It allows for investigation of the energy exchange between the vibration modes. These analytical derivations are later used to develop the instantaneously optimal control law and control algorithm as well as to select the measured quantities. Moreover, the control methodology includes dedicated metric of controllability of the energy transfer to/from particular vibration modes, which is used for selection of locations of lockable joints providing their efficient operation. Also a new convex-relaxation-based method for efficient sensor layout optimisation for the purpose of modal filtering is adopted. The control strategy has been validated both numerically and experimentally. It is demonstrated that due to the insight into modal coupling effects the proposed methodology mitigates low-frequency vibration requiring significantly smaller number of the joint state switches than the prestress accumulation–release (PAR) method that is adopted as a benchmark. Moreover, the proposed modal approach allowed for damping of particular vibration modes with assigned various priority levels, which is not possible in the PAR method. The proposed control algorithm also allows for significant enhancement of the energy harvesting process. It has been shown both numerically and experimentally that the control allows for precise energy transfer both towards lower frequencies and vice-versa.

PL

W niniejszej rozprawie skupiono się na nowej strategii półaktywnego sterowania modalnego, pozwalającego na precyzyjne przenoszenie energii pomiędzy poszczególnymi postaciami drgań konstrukcji mechanicznej. Sterowanie jest realizowane za pomocą blokowanych połączeń rotacyjnych – blokowanych węzłów – zainstalowanych w wybranych miejscach konstrukcji ramowej. Połączenie takie może być dynamicznie zablokowane i przenosić moment gnący między belkami konstrukcji lub być odblokowane i pracować jak zawias. Przenoszony moment gnący odpowiada za sprzężenie modalne, co skutkuje wymianą energii mechanicznej między postaciami drgań. Sterowanie ma zastosowanie zarówno w tłumieniu drgań, jak i usprawnianiu procesu odzyskiwania energii z drgań (energy harvesting). Praca obejmuje również inne aspekty strategii sterowania, takie jak optymalne rozmieszczenie sensorów do filtracji modalnej oraz optymalne rozmieszczenie blokowanych połączeń. Nowa strategia sterowania została zweryfikowana zarówno numerycznie, jak i eksperymentalnie.

10

Multiobjective optimization of efficiency, head, free passage and vibrations of two blade impeller for sewage pump with stationary front shroud

Sitniewski Mikołaj, Skrzypacz Janusz, Szulc Przemysław, Janczak Marcin, Lorenz Witold

Instal

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2025

|

nr 3

54--60

EN

This paper presents a multiobjective optimization procedure for a two-blade impeller in a sewage pump with a stationary front shroud. The optimization variables were the wrap angles on the front and back shroud, while the meridional cross-section and volute remained constant. The objective was to maximize efficiency, head, and free passage (e.g., minimizing blockage) while minimizing vibrations by reducing radial forces. A full factorial design with five levels was used for CFD (computational fluid dynamics) calculations. After selecting the optimal design, the results of initial and optimized impeller were validated experimentally. Numerical and experimental results demonstrated good agreement. The optimized impeller showed improvements: head increased by 38,4%, efficiency by 9,5%, and free passage by 8,3%. While CFD calculations predicted a reduction in averaged radial forces, vibration measurements on volute indicated an increase for the optimized impeller by 46,1%. This discrepancy suggests that radial forces may not be the primary factor influencing vibrations in this specific pump configuration. The findings of this study contribute to the development of more efficient and reliable sewage pumps.

PL

Artykuł przedstawia procedurę optymalizacji wielokryterialnej dwułopatkowego wirnika w pompie ściekowej z nieruchomą tarczą przednią. Zmiennymi optymalizacyjnymi były kąty opasania na tarczy przedniej i tarczy tylnej, podczas gdy przekrój meridionalny i spiralny korpus zbiorczy pozostały stałe. Celem było zmaksymalizowanie sprawności, wysokości podnoszenia i swobodnego przelotu przy jednoczesnej minimalizacji poziomu wibracji poprzez redukcję sił promieniowych. Do obliczeń CFD (computational fluid dynamics) zastosowano pełny plan czynnikowy z pięcioma poziomami. Po wybraniu optymalnego projektu, parametry pompy z wirnikiem początkowym i zoptymalizowanym zostały zweryfikowane eksperymentalnie. Wyniki numeryczne i eksperymentalne wykazały dobrą zgodność. Zoptymalizowany wirnik wykazał poprawę: wysokość podnoszenia wzrosła o 38,4%, sprawność o 9,5% i swobodny przelot o 8,3%. Podczas gdy obliczenia CFD przewidywały redukcję uśrednionych sił promieniowych, pomiary poziomu wibracji na spirali wskazały na wzrost dla zoptymalizowanego wirnika o 46,1%. Ta rozbieżność sugeruje, że siły promieniowe mogą nie być głównym czynnikiem wpływającym na poziom wibracji w tej konfiguracji pompy. Wyniki przedstawionych badań przyczyniają się do rozwoju pomp ściekowych o lepszych parametrach energetycznych i użytkowych.

11

Badanie właściwości tiksotropowych gruntu w aspekcie modernizacji wałów przeciwpowodziowych

Tanaś Magdalena, Sekuła Klaudia, Kaczmarczyk Robert

Gospodarka Wodna

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2025

|

Nr 9

15-19

PL

Artykuł podejmuje problematykę właściwości tiksotropowych gruntu oraz zachowania ośrodka gruntowego pod wpływem oddziaływań dynamicznych. Autorzy zwracają uwagę na brak metod badawczych umożliwiających jednoznaczne potwierdzenie występowania właściwości tiksotropowych gruntu, a także przedstawiają propozycję własnej metody badawczej. Opisowi poddano również model aparatury badawczej opracowanej w ramach projektu. Określenie właściwości tiksotropowych gruntu jest szczególnie istotne w kontekście oceny stanu technicznego oraz doboru odpowiednich technik wzmocnienia wałów przeciwpowodziowych, zwłaszcza przy wykorzystaniu technik wibracyjnych

EN

The article presents the issue of thixotropic properties of soil and soil medium response to dynamic actions. The authors point out to the lack of research methods that would enable unequivocal confirmation of the soil thixotropic properties occurrence and propose their own research method. The article also describes the research equipment model elaborated under the project. Determination of the soil thixotropic properties is of particular importance in the context of the assessment of the technical state of flood embankments and the choice of the appropriate techniques of their reinforcement, especially using the vibration techniques.

12

Variation analysis of a drive system with an innovative flexible clutch operating under the conditions of constant and cyclically variable load torque of diverse variation waveform

Wieczorek Andrzej, Wojnar Grzegorz, Konieczny Łukasz, Filipowicz Krzysztof, Kuczaj Mariusz, Pawlikowski Arkadiusz, Zawisza Maciej

Eksploatacja i Niezawodność

|

2025

|

Vol. 27, no. 4

art. no. 208868

EN

During machinery operation, load is often highly variable, which exerts an impact on how the machinery service life is reduced; hence the need for decreasing the variations in the load torque affecting the driving elements of machines. In order to achieve such reduction, the authors have developed a flexible clutch of innovative design. This paper provides a follow-up to the studies of the dynamic properties of the said clutch in terms of the analysis of the effect attributable to the input function waveform of the applied load on the dynamic response of the system, represented by the value of the accelerations of the drive system vibrations. The load variants analysed, with values of 500±250 Nm and 750±375 Nm (sinusoidal, triangular, and rectangular waveforms). On account of the fact that the flexible clutch was integrated with the drive system subject to the studies, it was found that the averaged maximum root mean square reductions of vibration accelerations in the measurement direction with the highest vibration accelerations (direction y) came as high as to 56.1%.

13

The use of wireless vibration sensors to monitor the technical condition of industrial fans

Witaszek Kazimierz, Duss Łukasz

Diagnostyka

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2025

|

Vol. 26, No. 4

art. no. 2025413

EN

The paper presents the practical application of a wireless vibration sensor system for the ongoing monitoring of the technical condition of industrial fans used in gas furnaces to heat metal billets prior to plastic working. During almost a year of research, vibration and temperature data was collected and subjected to time domain analysis. The measurement results were divided into weekly time intervals and statistically processed. In order to facilitate the decoding, segmentation into time-based segments, and statistical analysis of the research data, a software solution was developed. The application enabled the analysis of changes in weekly histograms and statistical parameters of data sets. A critical analysis was made of the statistical parameters obtained from the research material. The average weekly value of rms vibration acceleration and the highest weekly value of the relative frequency of data were selected as the parameters that best reflects changes in industrial fan technical condition. Functions modelling these changes were also developed. During the research, significant changes in the recorded vibration accelerations on fan motor No. 2 were observed. The developed functions proved useful for assessing and predicting changes in the technical condition of the tested fans.

14

Possibility of using polyurethane materials to reduce vibrations and noise in the working environment

Łakomy Karolina, Małysa Tomasz, Nowacki Krzysztof

Composites Theory and Practice

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2025

|

R. 25, nr 2

132-143

EN

Noise and vibrations are physical factors, the impact of which on the employee may negatively affect their health. Therefore, it is extremely important to effectively reduce the negative impact of these factors by implementing solutions that reduce the risk. In the article the possibility of using selected porous materials (layer systems) in the frequency range from f = 100 Hz to f = 2500 Hz, is presented. In order to assess the suitability of the application of the developed layer system, tests were carried out to determine the physical sound absorption coefficient (Kundt's tube), as well as to assess the effectiveness of vibration damping by polyurethane materials in the form of a layer system. It was found that the developed layer system can be used to reduce vibrations and noise. The developed layer system was characterized by the desired sound absorption properties αfśr > 0.6, in addition to damping efficiency above 50%, especially in the range of f = 315 Hz - 2500 Hz. The developed layered system took into account the frequency ranges characterized by the highest αf values (f = 1000-2500 Hz) as well as the effectiveness, aimed at a permanent reduction in physical factors (noise, vibrations) in the case of design solutions focused on limiting the negative impact of these factors on employees' health.

15

Analysis of the correlation between vibrations and the number of shorted turns in the stator winding of a squirrel-cage induction machine

Marczak Mikołaj, Pietrowski Wojciech, Górny Konrad

Archives of Electrical Engineering

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2025

|

Vol. 74, nr 2

341--359

EN

This paper presents a method of diagnosing a squirrel-cage induction motor based on the results of machine vibration analysis. The paper considers a fault involving an interturn short circuit in the winding of all phases of the stator. The waveforms of the diagnostic signals were recorded for selected configurations of winding shorts during steady state operation of the motor under constant torque load. In the next step of the study, wavelet packet decomposition was used to analyze the recorded waveforms of the vibration signals. The study focused on determining the correlation between the wavelet analysis results and the number of shorted turns. In addition, the effect of the wavelet used in the wavelet packet analysis on the correlation results was compared. As a result, a method was developed to detect shorted turns in the stator winding of an induction motor based on the results of wavelet packet analysis of the motor vibration.

16

Vibrations and impact forces of modified handle pneumatic hammer

Majewski Tadeusz, Meraz Melo Marco, Tracz Jan, Ładyżyńska-Kozdraś Edyta, Estrada Quirino

Advances in Science and Technology. Research Journal

|

2025

|

Vol. 19, no. 3

341--349

EN

The paper presents a dynamic model of a small electro-pneumatic percussive tool whose handle is elastically connected to the casing. The pneumatic force is defined as a function of the position of the piston and the striker. The Hertz model has been applied to the impact forces and given the conditions under which they exist. The differential equations define the movement of each part of the hammer. Their simulations show how the hammer parts vibrate, when the impacts occur, and how large the impact forces can be. The acceleration of the handle is determined and compared with the acceleration when the handle is part of the casing. The article proves that the hammer with a floating handle is better for the operator's protection.

17

Determining a damping coefficient by using a microelectromechanical systems accelerometer for finite element method simulation purposes on a discrete damper example

Flis Leszek, Szwoch Grzegorz, Krawczyk Piotr

Advances in Science and Technology. Research Journal

|

2025

|

Vol. 19, no. 6

275--290

EN

This paper introduces a methodology, algorithms, and the achieved results for determining the damping coefficient using a microelectromechanical systems (MEMS) accelerometer, specifically for finite element method (FEM) simulations. The paper not only showcases the results but also employs several independent verification procedures to confirm the validity of the obtained damping coefficient. The determined damping coefficient is presented directly in SI units, making it readily applicable to a specific object, while it is usually given as a percentage. The accuracy of the determined damping ratio was validated through unbiased experiments, an in-house computational Python program. Additionally, to ensure the correctness of the determined damping coefficient, a practical example was provided wherein FEM simulation was executed using a discrete element as a damper within ANSYS LS-Dyna software to corroborate the results. The authors emphasize that the proposed method for determining the damping coefficient is both efficient and can be implemented without the necessity of complex equipment. This novel methodology for assessing a damping coefficient serves as a promising alternative to Rayleigh Damping, which lacks a direct physical correlation. Moreover, it opens up significant possibilities for broader application in various engineering fields, including structural dynamics, vibration analysis, and mechanical system optimization.

18

Statistical Analysis of Frictional Processes of a Sliding Bearing

Lepiarczyk Dariusz

Tribologia

|

2024

|

nr 2

51--63

EN

This article addresses the issue of diagnosing friction nodes in sliding bearings, which are among the most challenging and complex topics in the tribological research. The article presents a methodology for diagnosing friction nodes operating under variable loads based on the analysis of vibration acceleration signals from the bearing using statistical methods. In the study, statistical parameters were determined to assess the technical condition of sliding bearings operating with variable loads under dry and mixed friction conditions. Using statistical tools to interpret selected tribological parameters that occur in the friction process aims to ensure the proper operation of the tribological system under operating conditions. Analysis of the measurement results presented in the study using statistical tools will allow the development of a methodology to assess the correct operation of sliding bearings.

PL

Praca podejmuje problem diagnozowania węzłów tarcia łożyska ślizgowego, które zalicza się do najbardziej trudnych i skomplikowanych w badaniach tribologicznych. W artykule przedstawiono metodykę diagnozowania węzłów tarcia pracujących przy zmiennym obciążeniu w oparciu o analizę sygnałów przyspieszeń drgań łożyska z wykorzystaniem metod statystycznych. W opracowaniu wyznaczono parametry statystyczne do określania stanu technicznego łożyska ślizgowego pracującego przy zmiennym obciążeniu w warunkach tarcia suchego i tarcia mieszanego. Wykorzystanie narzędzi statystycznych w interpretacji wybranych parametrów tribologicznych zachodzących w procesie tarcia ma na celu zapewnienie poprawnej pracy układu tribologicznego w warunkach eksploatacyjnych. Przedstawiona w opracowaniu analiza wyników pomiarów z wykorzystaniem narzędzi statystycznych pozwoli na opracowanie metodyki oceny poprawnego stanu pracy węzłów tarcia łożysk ślizgowych.

19

Vibration analysis of a MacPherson type suspension system

Georgiev Zlatin, Kunchev Lilo

Transport Problems

|

2024

|

T. 19, z. 3

193--202

EN

The road surface disturbs the pneumatic tyre in the contact patch withdifferent frequencies. The disturbing frequency depends on the speed of the vehicle andthe wavelength of the road irregularities. In the current study, the propagation of thevibrations created at the contact patch through the suspension is presented. The oscillationsare transmitted to the car body through the rubber mounts and the support joints. Whenthese vibrations reach body panels (roof and floor panels, windows, etc.), they aretransmitted to the air and, thus, the structure-borne noise in the passenger compartment iscreated. The structure-borne noise defines the vehicle comfort for the frequency range upto 400 Hz. The main task of noise, vibration, and harshness engineers is to avoid couplingbetween tyre and chassis elements’ natural modes, which significantly increases the levelof structural noise in the passenger compartment. The accelerations of the oscillations weremeasured for different points of the suspension and the car body. The measurements weretaken for two sets of tyres (summer and winter) of the same size and mounted on the samerims. The disturbing frequency was in the range of the tyre’s natural modes. The results forthe two sets of tyres were compared. The measurements were taken for different airpressure in them. This comparison shows the effect of the tyre type on the structure-bornepropagation and determines whether increased noise levels are due to the resonance of thetyre or a suspension element. In addition, a finite element analysis (FEA) was conducted.The model points out the exact element responsible for the high levels of vibrations. Thus,the coupling between the tyre and suspension natural modes can be avoided.

20

Assessment of the technical state of mining machinery and devices with the use of diagnostic methods

Biały Witold

Production Engineering Archives

|

2024

|

Vol. 30, Iss. 2

266--272

EN

In this article, one of the possible, effective methods of assessing the technical state of mining machinery and devices has been presented. The article's main goal is to show the possible methods and ways of measuring temperature, oscillations, and vibrations generated during the operation of mining equipment and machines’ gears, which are possible in underground conditions. Devices measuring temperatures without coming into contact with the given object are built based on different types of infrared radiation detectors or matrixes of such detectors. Thermal imaging devices picture the temperature distribution on the entire surface instead of pyrometers, which measure temperatures at a given point. However, vibrations and oscillations generated by the work of gears of devices and machinery have been made using a vibrometer pen and a machine condition tester, after which the obtained measurements were used to diagnose the degradation of individual elements of those machines. Such an assessment of the degradation of individual elements of machines in production conditions has been applied with positive results in one of the mines of the Polish Mining Group (Polska Grupa Górnicza – PGG).