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1

Effect of the turbulent oil film on the dynamic characteristics of two-lobe journal bearings

Strzelecki Stanislaw Kazimierz

Engineering Transactions

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2025

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Vol. 73, iss. 2

219--232

EN

Turbogenerators in power plants utilize two-lobe journal bearings, which can carry large loads with good stability at the speeds typically encountered in the power industry. These bearings feature the profiles such as elliptical, offset, cylindrical or pericycloidal. The design of these bearings ensures proper load capacity, favorable thermal conditions for the oil film, and stable operation of the associated turbounits. However, the design of these bearings should be supported by calculations that account for turbulence generated in the oil film. This paper presents the results of dynamic characteristic calculations for four types of two-lobe journal bearings operating under adiabatic laminar or turbulent flow conditions in the lubricating gap. The dynamic characteristics, expressed as the stiffness and damping coefficients of the oil film, were obtained using the perturbation method. Stability ranges for a simple symmetric rotor were determined for the considered bearings. A numerical algorithm for the iterative solution of the Reynolds, energy and viscosity equations was employed to calculate the oil film forces, which formed the basis for the bearing’s dynamic characteristics. These investigations were carried out assuming the static equilibrium position of the journal.

2

Research on mechatronics integration modelling and coupled dynamic characteristics in a shearer cutting section gearbox

Lu Wenjia, Zhang Yimin, Du Zunling, Huang Weibo

Archives of Mining Sciences

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2025

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Vol. 70, no. 1

115--145

EN

The time-varying mesh stiffness (TVMS) and static transmission error (STE) are the main dynamic load excitation forms in the shearer cutting section gearbox (SCSG). The gearbox comprises two-stage planetary gear sets and multi-stage parallel gear sets. The structure of the multi-stage transmission and its rich internal dynamic excitation result in unique and complex dynamic behavior. In this paper, a coupled mechatronic integration dynamic model for SCSG and motor is developed, in which the multi-stage coupling excitation effects caused by gear mesh stiffness and static transmission error are fully simulated, thereby clarifying the interaction mechanism between the motor and transmission system. Based on the simulation model, the dynamic load characteristics of the SCSG are studied. The results show that load-sharing performance is improved with the increases of drum torque in the planetary gear sets (PGSs), which indicates that the load-sharing performance of the planetary gears can be effectively guaranteed in the process of increasing the coal mining rate. Through the combination of numerical simulation and experimental research, it is verified that the simulated signals are consistent with the experimental data for motor current. Meanwhile, relying on the proposed mechatronics model, extensive vibration information of the gearbox can be identified through the stator current signal. These results reference the vibration response analysis and signal monitoring of complex transmission systems.

3

Estimating fundamental frequency of masonry arches under elevated temperature: numerical analysis and validation using ambient vibration tests

Altunişik Ahmet Can, Öztürk Muhammed Mustafa, Genç Ali Fuat, Kaya Ali, Akbulut Yunus Emrahan, Sunca Fezayil, Günaydin Murat

Archives of Civil and Mechanical Engineering

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2025

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Vol. 25, no. 1

art. no. e23, 2025

EN

In this study, the changing of dynamic characteristics of masonry arches at varying geometric parameters and temperature histories was investigated through a combination of experimental and numerical methods. First, the dynamic characteristics of laboratory-built arch models were determined both pre- and post-high-temperature test using ambient vibration testing. Then, the finite element (FE) models of the arches were developed for both, allowing for dynamic characteristics to be assessed numerically. To refine the accuracy of numerical models, FE analyses were adjusted based on experimental data. These updated FE models were used to investigate the dynamic characteristics of arches with different spans, heights, widths, and thicknesses under different temperature history scenarios. Finally, utilizing the data repository obtained, formulation and graphs/charts, providing valuable insights into the dynamic response of masonry arches under fire conditions, were developed and presented for practical application. The experimental study revealed that the natural frequencies of arches decreased by 55% with increasing temperature exposure.

4

Device for dynamic calibration of pressure sensors

Tykhan Myroslav, Markovych Viktor, Heneralov Vitalii, Milian Marian

Metrology and Measurement Systems

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2024

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Vol. 31, nr 4

657--671

EN

Modern devices for dynamic calibration of pressure sensors (shock tubes, power simulators of pressure impulse, etc.) have a number of drawbacks stemming from the principles of creating a test impact. Besides, the problem of rational choice of the method of calibrating pressure sensors depending on the dynamic parameters of the sensor and the required test accuracy has not been solved for modern test systems. The paper presents a solution to the problem of correlation between the test parameters, dynamic parameters of the pressure sensor and test accuracy. The obtained analytical dependencies of such a relationship make it possible to reasonably select or develop a method for studying the dynamic characteristics of sensors. Based on theoretical studies, the principle of creating a test impact has been proposed, and a method and device for implementing dynamic calibration of pressure sensors have been devised. The developed device allows the transient response of the sensor to be obtained, as well as setting the decay time of its natural vibration. Based on the transient response, other dynamic characteristics of the sensor, namely the impulse transient and frequency response, can be calculated.

5

Random eigenvibrations of beams with viscoelastic layers

Kamiński Marcin, Przychodzki Maciej, Łasecka-Plura Magdalena, Guminiak Michał, Lenartowicz Agnieszka

Journal of Theoretical and Applied Mechanics

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2024

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Vol. 62 nr 4

763--767

EN

This paper is devoted to the study of the influence of random variation of model parameters of a beam with viscoelastic layers on probabilistic characteristics of its natural frequencies and dimensionless damping coefficients. The relationships between the model parameters and the dynamic characteristics of the beam were approximated by quartic polynomials based on the results of calculations using FEM, where beam finite elements were used, taking into account lamination of the beam. The nonlinear eigenproblem was solved using the continuation method. The calculation results for an example laminated beam are presented.

6

Influence of Shock Absorber on Electric Axle Vibration in Semi-Trailer

Stembalski Marek, Szydlowski Tomasz, Czarnuch Arkadiusz

Journal of Machine Engineering

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2024

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Vol. 24, No. 3

119--132

EN

This article describes the results of a study of the effect of a shock absorber on the vibration of an electric axle in a semi-trailer. The dynamic characteristics of three shock absorbers from different manufacturers were determined. They were then installed on the electric axle of a semi-trailer equipped with a measuring apparatus. Test runs were carried out on two types of road surface - a test track with a defined profile and a local road. Each run was repeated for a fully loaded and an empty semi-trailer. These tests were designed to determine the values of the dynamic parameters of the electric axle during operation of the semi-trailer depending on the shock absorber used.

7

Analyzing frequency response analysis experimentally for bone healing detection: examining the potential of vibrational evaluations

Kadhim Abbas Jawad, Aubad Mohammed Jawad, Al-Juboori Ameen M.

Diagnostyka

|

2024

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Vol. 25, No. 3

art. no. 2024315

EN

Assessment of bone healing is essential for efficient orthopedic treatment. This work investigates the feasibility of assessing frequency response experimentally for bone healing detection, with a particular emphasis on the use of vibrational assessments. Detailed experimental studies were carried out to determine the ability of frequency response analysis to assess bone healing. Mechanical excitation was delivered to cracked bone samples at various frequencies, and the vibrational responses of the displacement and accelerations were measured. The experimental setting includes testing five samples, to cover a wide range of possibilities. The obtained vibrational, such phase, magnitude, and coherence, were examined to find common patterns and changes linked with the healing process. The results showed that frequency response analysis has the potential to identify bone healing, as unique vibrational responses were seen in healed samples under cyclic load for different turns (0, 1000, 2000, 3000, and 4000). The findings demonstrate the sensitivity of vibrational evaluations in capturing the mechanical properties and healing condition of bone tissue. Furthermore, the presence of cracks impacts both structural integrity and natural frequency. Natural frequency decreases as the number of cycles increases. The highest frequency reduction occurred at the first mode shape and maximum cycle number, indicating considerable fracture behaviour changes. Natural frequency can be used to assess bone health; higher stiffness and frequency are associated with smaller crack size.

8

Innovative Design and Machining Verification of a Dual-Axis Swivel Table for a Milling Machine

Lin Wei-Zhu, Xiao Jian-Xuan, Lin Yung-Chih, Chang Bo-Wei, Hung Jui-Pin

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 1

306--319

EN

This study was aimed to develop a dual-axis rotary table for small and medium-sized five-axis milling machines. The rotation and tilting axis of swivel table were respectively driven by servo motor with gear reducer to achieve low speed, high torque, high rigidity and high precision machining capability. Essentially, the dynamic interaction between the work piece and the tool in the cutting process is an important factor that affects the machining performance, which also implies that the structural characteristics of the rotary table with the swiveling angle will affect the cutting performance of the five-axis machine. Therefore, at the design stage of a five-axis machine tool, it is a prerequisite to evaluate change of dynamic characteristics of the rotary module within the desired feeding range. To this purpose, this study employed the finite element method to analyze the dynamic characteristics of the rotary table under different configurations. In order to evaluate the application feasibility of the dual axis module on a milling machine, ISO S-shaped machining tests were carried out. Meanwhile, considering the influence of machining vibration on the surface quality of the work piece, the vibration induced at spindle tool and rotary table were assessed for comparisons and used to evaluate the variation of machining vibration with the milling cycles. Based on various experimental results, it is confirmed that the proposed dual-axis rotary table has good structural dynamic characteristics with stable vibration features during a small batch production tests. Current results clearly demonstrate the potential and capability of the proposed dual axis rotary table in practical application and commercialization.

9

Influence of the suspension shape on the dynamic characteristics of the electrodynamic shakers

Augustyn Damian, Fidali Marek

Vibrations in Physical Systems

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2023

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Vol. 34, nr 2

art. no. 2023227

EN

Electrodynamic shakers are being used for years in dynamic tests of machines and devices. One of the main components of electrodynamic shakers is the armature suspension. Suspension is one of the factors responsible for the dynamic characteristics of the shaker. Various types of suspensions are used in shakers [1, 2]. Their role is to ensure the correct stroke of the armature and to keep the coil concentrically in the magnetic gap. As part of the research, the influence of the shape of the suspension springs of the electrodynamic shaker on its dynamic characteristics was evaluated. During the research, self-designed electrodynamic shaker was used, in which a suspension consisting of two-disc springs made of glass fiber with a thickness of 0.5 mm was used. Eight different spring types were prepared for the study. The tests were carried out in laboratory conditions on a previously prepared test bench. For each of the springs tested, dynamic frequency characteristics were determined for three frequency ranges: 10 - 100 Hz with a step of 10 Hz, 100 Hz - 1000 Hz and 1000 Hz - 10000 Hz with a step of 100 Hz. Studies show a significant influence of the shape of the springs used on the dynamic characteristics of the modal shaker. For the preselected springs, tests were carried out without and with a load. The characteristics determined during the research were analyzed, which allowed to indicate the optimal shape of the spring, due to the values of the generated force and the linearity of the dynamic characteristics [3, 4].

10

Dynamic characteristics of the multilobe journal bearings with the lobes of different geometry

Strzelecki Stanislaw

Vibrations in Physical Systems

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2023

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Vol. 34, nr 2

art. no. 2023225

EN

Multilobe journal bearings are applied in different types of rotating machines such as, e.g. turbounits. The design of such bearings assures proper load capacity, thermal conditions of oil film and stability of the operation of responsible turbounits. However, the design of these bearings can be changed by application of lobes with different geometries. It allows obtaining new family of the dynamic characteristics. The paper presents the multilobe journal bearings with 2- and 3-lobes characterized by different geometry of lobes. The dynamic characteristics in form of the stiffness and damping coefficients of oil film were obtained by perturbation method. Stability ranges of simple symmetric rotor were determined for considered bearings. The iterative solution of Reynolds, energy and viscosity equations allows the obtaining the oil film forces, which were the basis of the bearing dynamic characteristics. Adiabatic, laminar oil film and the static equilibrium position of journal were assumed.

11

Analysis of dynamic characteristics of an experimental bench of high-pressure water fracturing assisted cutting

Liu Zhiming, Zhang Qiang, Sun Yuliang, Liu Junming

Journal of Theoretical and Applied Mechanics

|

2023

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Vol. 61 nr 2

317--330

EN

Aiming at the problem that the cutting efficiency of a drum shearer is low when mining hard coal seams, an experimental bench of high-pressure water fracturing assisted cutting is designed. Compared with normal ones, the maximum equivalent stress of the improved experimental bench is reduced by 55.38%, and the maximum total deformation is reduced by 27.23%. According to the results of dynamic response analysis, it is concluded that the experimental bench of high-pressure water fracturing assisted cutting is stable and reliable under extreme working conditions, and meets design requirements for strength and stiffness.

12

Experimental dynamic damage assessment of PUFJ protected brick infilled RC building during successive shake table tests

Kwiecień Arkadiusz, Rakicevic Zoran, Chełmecki Jarosław, Bogdanovic Aleksandra, Tekieli Marcin, Hojdys Łukasz, Gams Matija, Krajewski Piotr, Manojlovski Filip, Soklarovski Antonio, Halici Omer Faruk, Rousakis Theodoros, Vanian Vachan

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2023

|

Vol. 71, nr 3

art. no. e144940

EN

It is highly important to determine eigenvalues before and after certain extreme events that may cause damage accumulation, such as earthquake, blasts and mining or seismic tests on research models. Unique experiment design and shake table testing was performed to investigate seismic performance of a 3D RC building model with infill walls and advanced protection with polyurethane-based joints and fiber polymer reinforced light and emergency jackets. For the purpose of wider experimental activities, three methods for determination of the dynamic characteristics were used during multiple successive shake table tests following a dynamic pushover approach, and they are presented in detail. They are: inertance function through impact hammer tests, standard Fourier transformation of measured acceleration time history and digital image correlation. The expected differences in the results are related to the type and intensity of excitation used, the involvement of materials with different mechanical and physical properties, and with the different rate and extent of damage accumulation, as well as to local or global measurements. Y et, all methods lead to reliable results when a consistent methodology is being used, that takes into account locality or globality of measurements, leaving a choice for the most suitable one, depending on the site conditions. The inertance function method presented manifested its high efficiency in analysis of dynamic properties of large-scale structures and in monitoring of their changes caused by the damage and repair process. It offers quite a wide range of useful information, does not require very expensive equipment and its transportation cost is negligible. This method seems to be a proper diagnostic tool for simple experimental modal analysis of real structures and their structural elements, where detection of changes in the structural condition and in dynamic properties is required, also as a non-destructive testing and monitoring method. Digital image correlation proved to be a promising non-contact tool, strongly supporting the conventional instrumentation of shake table testing, while the Fourier transformation was used as a benchmark method yielding the most reliable results.

13

Influence of anchoring and bracing system on dynamic characteristics of façade scaffolding

Bęc Jarosław

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

493--506

EN

The basic dynamic characteristics of façade scaffolding are natural frequencies of vibrations and corresponding mode shapes. These properties affect the scaffolding safety, as well as comfort and safety of its users. Many of the dynamic actions present at scaffolding are in the low frequency range, i.e. below 10-15 Hz. The first natural frequency of a structure is usually in the range of 0.7 to 4 Hz which corresponds to resonant frequencies of human body and it means that vibrations induced at scaffolding may strongly affect the human comfort. The easiest way of increasing the rigidity of the structure is by ensuring correct boundary conditions (support, anchorage) and bracing of the structure. The numerical analysis was performed for the real scaffolding structure of medium size. The analysis consisted of natural frequencies calculation for the original structure and for models with modified bracing and anchoring systems. The bracing modifications were introduced by reducing or increasing the number of vertical bracing shafts. The anchor system was modified by reduction of the 6 anchors in the top right corner of the scaffolding in three stages or by evenly removing nearly 1/3 of the total number of anchors. The modifications of bracing and anchor systems resulted in changing the natural frequencies. The increase of natural frequencies due to higher number of anchors and more bracing is not even for all mode shapes. Bracing is more effective in acting against longitudinal vibrations, while anchoring against vibrations perpendicular to the façade.

PL

Rusztowania fasadowe to tymczasowe konstrukcje użytkowe wspomagające prace budowlane. Istotne jest zapewnienie bezpieczeństwa konstrukcji i pracowników, a także komfortowych warunków pracy ich użytkownikom poprzez zmniejszenie poziomów drgań docierających do nich. Podstawowe charakterystyki dynamiczne rusztowań fasadowych to częstotliwości drgań własnych oraz odpowiadające im postacie drgań. Pierwsza częstość drgań własnych w przypadku konstrukcji tego typu zazwyczaj mieści się w zakresie od 0,7 do 4 Hz, a więc są to wielkości zgodne z częstościami generowanymi przez wiele urządzeń działających na rusztowaniu, a także są one zbliżone do częstości rezonansowych części ciała ludzkiego. Częstotliwość drgań własnych uzależniona jest od rozmiarów rusztowania, jego masy oraz masy dodatkowej zgromadzonej na rusztowaniu (materiały budowlane, siatki ochronne i plandeki, użytkownicy rusztowania), a także od sztywności konstrukcji. Projektant pojedynczego rusztowania nie ma wpływu na elementy katalogowe systemu rusztowaniowego. Możliwe jest jednak zwiększenie sztywności rusztowania poprzez odpowiednio zaprojektowany system kotwienia konstrukcji rusztowania i przez prawidłowe stosowanie stężeń. Wymagany układ stężeń oraz rozstawy zakotwień w typowych rusztowaniach fasadowych można znaleźć w przepisach normowych lub katalogach producentów systemów rusztowań. Przeprowadzono obliczenia komputerowe przykładowego rusztowania fasadowego o średniej wielkości. Model metody elementów skończonych został stworzony w programie Autodesk Simulation Multiphysics 2013. Oryginalny model zawierał stężenia i zakotwienia zaproponowane przez projektanta konstrukcji rusztowania na podstawie wymagań producenta systemu. W kolejnych wariantach modyfikacji ulegała liczba pionów ze stężeniami, tj. z oryginalnej liczby pionów stężeń (3) pozostawiono 2 (rusztowanie słabo stężone), a następnie liczbę pionów stężeń zwiększono do 5 (rusztowanie przesztywnione). Podobnie, analizie poddano wpływ liczby zakotwień. Założono, że fragment konstrukcji pozostaje niezakotwiony, co wprowadzono do modelu przez eliminację 6 kotew w trzech etapach. Ostatni wariant modyfikacji oryginalnego sytemu zakotwień to równomierne usunięcie 10 spośród 36 ogółem punktów zakotwień. Wyniki obliczeń zostały zebrane w postaci pierwszych dziesięciu częstości drgań własnych. Analizowano także postacie drgań własnych, odpowiadające zbliżonym częstościom drgań. Zwiększenie liczby stężonych pól i większa liczba zakotwień powoduje zwiększenie częstotliwości drgań własnych. Nie jest to jednakowa zmiana dla wszystkich częstości i postaci. Stężenia mają większy wpływ na postaci związane z drganiami poziomymi wzdłuż fasady, podczas gdy liczba zakotwień wpływa istotnie na wartości związane z postaciami z przemieszczeniami prostopadle do fasady. Pozostawienie dużego obszaru pozbawionego zakotwień powoduje znaczne zmniejszenie przede wszystkim pierwszej częstości drgań własnych. Taka sytuacja jest niedopuszczalna, a mimo to spotykana w przypadku rusztowań zlokalizowanych przy istniejących budynkach, gdzie z powodów technologicznych kotwienie części konstrukcji jest utrudnione i czasem przez projektantów zaniedbywane. Należy również mieć na uwadze, że niedostateczne kotwienie i stężenie rusztowań fasadowych ma wpływ nie tylko na ich charakterystyki dynamiczne, ale także na wytężenie elementów konstrukcji. Może to prowadzić do stanów awaryjnych, mimo nieprzekroczenia dopuszczalnych wielkości obciążeń.

14

A comparative study of the sensitivity analysis for systems with viscoelastic elements

Łasecka-Plura Magdalena

Archive of Mechanical Engineering

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2023

|

LXX, nr 1

5--25

EN

This paper discusses the different methods used for calculating first- and second-order sensitivity: the direct differentiation method, the adjoint variables method, and the hybrid method. The solutions obtained allow determining the sensitivity of dynamic characteristics such as eigenvalues and eigenvectors, natural frequencies, and nondimensional damping ratios. The methods were applied for analyzing systems with viscoelastic damping elements, whose behavior can be described by classical and fractional rheological models. However, the derived formulas are general and can also be applied to systems with damping elements described by other models. Their advantage is a compact and easy to code form. The paper also presents a comparison of the computational costs of the discussed methods. The correctness of all the proposed methods has been illustrated with numerical examples.

15

Wybrane charakterystyki dynamiczne kładek dla pieszych z pomostami z betonu UHPC

Pańtak Marek

Inżynieria i Budownictwo

|

2022

|

R. 78, nr 11-12

568--573

PL

W artykule przedstawiono wybrane charakterystyki oraz wyniki badań i analiz dynamicznych dwóch kładek dla pieszych wzniesionych z wykorzystaniem betonu UHPC. Zobrazowano wpływ wykorzystania betonu UHPC na parametry dynamiczne kładek dla pieszych.

EN

The article presents selected characteristics and the results of dynamic tests and analyses of two footbridges built with the use of UHPC concrete. The influence of the use of UHPC concrete on the dynamic parameters of footbridges was depicted.

16

Dynamic characteristics of underframe semi-active inerter-based suspended device for high-speed train based on LQR control

Wang Yong, Li Hao-Xuan, Meng Hao-Dong, Wang Yang

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2022

|

Vol. 70, nr 4

art. no. e141722

EN

The underframe passive inerter-based suspended device, based on the inerter-spring-damper vibration attenuation structure, could improve the dynamic performance of the train body, but its parameters are fixed and cannot meet the dynamic performance requirements under different operating conditions. Therefore, a semi-active inerter-based suspended device based on the linear quadratic regulator (LQR) control strategy is proposed to further enhance the dynamic performance. The rigid-flexible coupling vertical dynamic model of the train body and an underframe semi-active inerter-based suspended device are established. The structural parameters of the semi-active inerter-based suspended device are adjusted using LQR control strategy. Dynamic response of the system is obtained using the virtual excitation method. The dynamic characteristic of the system is evaluated using the Sperling index and compared with those of the passive and semi-active traditional suspended devices as well as the passive inerter-based suspended devices. The vertical vibration acceleration of the train body and Sperling index using the semi-active inerter-based suspended device is the smallest among the four suspended devices, which denotes the advantages of using the inerter and LQR control strategy. The semi-active inerter-based suspended device could decrease the vertical vibration acceleration of the train body and further suppress its elastic vibration in the lower frequency band, more effectively than the other three suspended devices. Overall, the semi-active inerter-based suspended device could significantly reduce elastic vibration of the train body and improve its dynamical performance.

17

Dynamics of large diameter hydraulic legs under applied test methods

Stoiński Kazimierz, Płonka Marek, Świątek Janina

Archives of Mining Sciences

|

2022

|

Vol. 67, no. 2

259--273

EN

The dynamic characteristics of the hydraulic leg are essential for determining the safe working range of roof supports operating in seams threatened by rock mass tremors. The systematic increase in the support of the hydraulic legs due to deteriorating geological-mining conditions has increased their diameters, which currently exceed 0.32 m for the 1st hydraulic stage. Evaluation of the dynamic properties of the roof support and the hydraulic legs are carried out by the Central Mining Institute through calculation methods as an implementation of the Regulation of the Minister of Energy on occupational safety and health. However, the issue of validating the calculations concerning natural scale studies still needs to be addressed. There are significant limitations in this area due to the technical and metrological capabilities of the testing stations. This paper presents an attempt to evaluate bench testing of a hydraulic leg with 0.32 m of the 1st hydraulic stage diameter for the validation of computational and test methods. Results of previous studies affecting the evaluation of the research methods used are also cited. According to the authors, the optimal and economically justifiable direction is to undertake model tests using numerical analyses and to validate these results, based on the study of models of hydraulic legs that are in use at a reduced scale. The construction of testing stations to ensure adequate dynamic loading for the support of the largest diameter hydraulic legs is currently not economically viable. The problem presented, however, is important given the constantly deteriorating geological-mining conditions and the associated threat of rock mass tremors.

18

Sperling’s comfort index study in a passenger car with independently rotating wheels

Vaičiūnas Gediminas, Steišūnas Stasys

Transport Problems

|

2021

|

T. 16, z. 2

121--130

EN

In this article, we compare the dynamic characteristics of cars with integral wheelsets and wheelsets with independently rotating wheels. We use Sperling’s comfort index to assess the riding comfort. We compare the riding comfort of passenger cars with integral wheelsets and wheelsets with independently rotating wheels based on Sperling’s comfort index.

19

Analysis of dynamic characteristics of selected pneumatic systems with rractional calculus. simulation and laboratory research

Luft M., Krzysztoszek K., Pietruszczak D., Nowocień A.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2021

|

Vol. 15 No. 4

835--843

EN

The section of the paper on simulation studies presents the application of fractional calculus to describe the dynamics of pneumatic systems. In the construction of mathematical models of the analysed dynamic systems, the Riemann-Liouville definition of differ-integral of non-integer order was used. For the analysed model, transfer function of integer and non-integer order was determined. Functions describing characteristics in time and frequency domains were determined, whereas the characteristics of the analysed systems were obtained by means of computer simulation. MATLAB were used for the simulation research. The section of the paper on laboratory research presents the results of the laboratory tests of the injection system of the internal combustion engine with special attention to the verification of simulated tests of selected pneumatic systems described with the use of fractional calculus.

20

Risk assessment of packed holeassembliesfor rotary well drilling

Myslyuk Mykhailo, Dolyk Ruslan

Journal of Geotechnology and Energy

|

2021

|

Vol. 38, no. 1

41--46

EN

The main elements of the statistical model of packed hole assemblies (PHA) design for drilling holding sections in conditions of information uncertainty are formalized and described. A constraint system has been given for the angle maintenance conditions of wellbore direction and dynamic stability of bottom hole assembly (BHA) lateral vibrations. The influence of the information uncertainty of some factors (angle, parameters of the drilling practice, presence of local caverns, etc.) on risk indicators has been analyzed according to the results of the numerical calculations. It has been determined that the risks of angle maintenance disturbance are significantly influenced by the angle and weight on the bit (WOB), and dynamic stability conditions, such as angle and rotation frequency. Risks of multi-supported BHAs which have been designed for conditions of minimizing bit side force, dynamic stability and include 4-6 stabilizers.