PL
 |
EN
Ograniczanie wyników
Czasopisma help
  1. 5 Vibrations in Physical Systems
  2. 4 Inżynieria i Budownictwo
  3. 3 Czasopismo Techniczne. Budownictwo
  4. 3 Journal of Theoretical and Applied Mechanics
  5. 3 Machine Dynamics Research
Więcej...
Autorzy help
  1. 6 Strzelecki S.
  2. 5 Lewandowski R.
  3. 3 Kyzioł L.
  4. 3 Sawicki A.
  5. 3 Sosiński R.
Więcej...
Lata help
  1. 1 2024
  2. 6 2023
  3. 3 2022
  4. 5 2021
  5. 3 2020
Więcej...
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 74

Liczba wyników na stronie
first rewind previous Strona / 4 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  dynamic characteristics
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 4 next fast forward last
1
Content available 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
|
2024
|
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.
2
Content available remote Influence of the suspension shape on the dynamic characteristics of the electrodynamic shakers
Augustyn Damian, Fidali Marek
Vibrations in Physical Systems
|
2023
|
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].
3
Content available Dynamic characteristics of the multilobe journal bearings with the lobes of different geometry
Strzelecki Stanislaw
Vibrations in Physical Systems
|
2023
|
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.
4
Content available 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
|
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.
5
Content available 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.
6
Content available Influence of anchoring and bracing system on dynamic characteristics of façade scaffolding
Bęc Jarosław
Archives of Civil Engineering
|
2023
|
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.
7
Content available A comparative study of the sensitivity analysis for systems with viscoelastic elements
Łasecka-Plura Magdalena
Archive of Mechanical Engineering
|
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.
8
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.
9
Content available 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.
10
Content available 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.
11
Content available 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.
12
Content available 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.
13
Content available 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.
14
Content available The use of synthesis methods in position optimisation and selection of tuned mass damper (TMD) parameters for systems with many degrees of freedom
Dymarek Andrzej, Dzitowski Tomasz
Archives of Control Sciences
|
2021
|
Vol. 31, No. 1
185--211
EN
The paper formulates and formalises a method for selecting parameters of the tuned mass damper (TMD) for primary systems with many degrees of freedom. The method presented uses the properties of positive rational functions, in particular their decomposition, into simple fractions and continued fractions, which is used in the mixed method of synthesis of vibrating mechanical systems. In order to formulate a method of tuning a TMD, the paper discusses the basic properties of positive rational functions. The main assumptions of the mixed synthesis method is presented, based on which the general method of determining TMD parameters in the case of systems with many degrees of freedom was formulated. It has been shown that a tuned mass damper suppresses the desired resonance zone regardless of where the excitation force is applied. The advantages of the formulated method include the fact of reducing several forms of the object’s free vibration by attaching an additional system with the number of degrees of freedom corresponding to the number of resonant frequencies reduced. In addition, the tuned mass damper determined in the case of excitation force applied at a single point can be attached to any element of the inertial primary system without affecting the reduction conditions in this way. It results directly from the methodology formalised in the paper. As part of the paper, numerical calculations were performed regarding the tuning of the TMD to the first form of free vibration of a system with 3 degrees of freedom. The parameters determined were subjected to analysis and verification of the correctness of the calculations carried out. For the considered case of a system with 3 degrees of freedom together with a TMD, time responses of displacement, from each floor, were generated to excitation induced by a harmonic force equal to the first form of vibration of the basic system. In addition, in the case of the parameters obtained, the response of the inertial element system to which the TMD was attached to random white noise excitation was determined.
15
Content available Experimental identification of dynamic characteristics of a track structure influencing the level of noise emission
Kraśkiewicz Cezary, Mossakowski Przemysław, Zbiciak Artur, Al Sabouni-Zawadzka Anna
Archives of Civil Engineering
|
2021
|
Vol. 67, nr 4
543--557
EN
The present paper describes an experimental methodology of identification of dynamic characteristics of a track structure, consisting in determination of a track decay rate (TDR) in the field tests that were conducted by the authors on the railway line section in Warsaw. The proposed methodology of measurements, parameters determination and presentation of the results is based on the measurement methods described in EN 15461 [1], which are aimed at determination of TDR. The values of TDR determined in the impulse tests in one-third octave bands are compared with the limiting values specified in EN ISO 3095 [2] and Technical Specifications for Interoperability (TSI) [3]. Based on the obtained experimental data, the analysed railway line is classified as a structure that does not generate excessive level of rolling noise from the vibrations induced by the moving rolling stock on structural elements of the track - particularly on rails. The results obtained in this study are promising from the point of view of future development of effective solutions used for protection of people and environment against noise generated by the railway traffic.
PL
W artykule przedstawiono doświadczalną metodykę badawczą wyznaczania charakterystyk dynamicznych nawierzchni kolejowej poprzez badania poligonowe współczynnika zanikania drgań wzdłuż szyny zrealizowane przez autorów na odcinku linii kolejowej w Warszawie. Jako podstawę w odniesieniu do metodologii pomiaru, wyznaczenia i prezentacji wyników wykorzystano metodykę pomiarową opisaną w normie europejskiej EN 15461, której celem jest wyznaczenie współczynnika zanikania drgań wzdłuż szyny (ang. Track Decay Rate, w skrócie TDR). Najnowsze trendy w transporcie szynowym, zakładają jak największe wykorzystanie przepustowości tras m.in. poprzez wzrost prędkości pojazdów, a tym samym skrócenie czasu przejazdu. Negatywnym skutkiem takich działań jest jednak m.in. zwiększenie poziomów emisji hałasu do środowiska. W przypadku ludzi ma to ujemny wpływ na ich zdrowie, zmniejsza wydajność pracy, utrudnia wypoczynek i koncentrację, a więc ogólnie, zmniejsza komfort życia w strefie takich oddziaływań. Aby zminimalizować te negatywne oddziaływania stosuje się różne rozwiązania, które w strefie emisji, tj. strefie kontaktu kół i szyn polegają m.in. na usuwaniu nierówności na ich powierzchniach tocznych poprzez profilowanie szyn oraz kół. Innym sposobem ograniczania emisji fali akustycznej są działania podejmowane w konstrukcji drogi kolejowej, polegające na optymalizacji sprężystych charakterystyk tej konstrukcji - głównie sprężystego podparcia i mocowania szyn poprzez zastosowanie odpowiednich elementów i warstw konstrukcyjnych. Oprócz funkcji mechanicznych związanych z przenoszeniem dynamicznych obciążeń od ruchu pojazdów szynowych, elementy te spełniają funkcje izolatorów wibroakustycznych, które ograniczają transmisję drgań pomiędzy elementami składowymi konstrukcji nawierzchni szynowej - głównie elementami systemów przytwierdzenia szyn. W niniejszej pracy przedstawiono wyniki badan poligonowych, w ramach których mierzono metodą impulsową współczynnik TDR. Badania przeprowadzono na czasowo zamkniętej łącznicy wzdłuż linii kolejowej nr 501, tor nr 1 w Warszawie. Celem badań była przede wszystkim weryfikacja przewidywanego wpływu elementów składowych nawierzchni kolejowej na wartość współczynnika TDR. Wartość tego parametru pozwala wnioskować o poziomie emisji hałasu, ponieważ istnieje silny związek pomiędzy współczynnikiem TDR a intensywnością emisji hałasu toczenia przez elementy składowe nawierzchni kolejowej (np. szyny). Wyznaczone metodą impulsową w badaniach terenowych wartości współczynnika TDR w tercjowych pasmach częstotliwości odniesiono do wartości granicznych określonych w normie europejskiej EN ISO 3095 oraz Technicznych Specyfikacjach Interoperacyjności (TSI). Na bazie wyników badań empirycznych zakwalifikowano analizowaną linię kolejową jako nie generującą nadmiernego poziomu hałasu toczenia od drgań elementów składowych nawierzchni kolejowej wzbudzonych przez przejeżdzające pojazdy szynowe.
16
Content available Dynamic modeling and analysis of helical gear-shaft-bearing coupled system
Bai Huan, Song Chaosheng, Zhu Caichao, Wang Yawen, Ou Zhuxiang
Journal of Theoretical and Applied Mechanics
|
2020
|
Vol. 58 nr 3
743--756
EN
Considering bearing clearance, time-varying mesh stiffness, time-varying transmission error and shaft flexibility, a coupled gear-shaft-bearing dynamic model for a helical gear transmission is established. The influences of rotating speed, input torque load and bearing clearance on the dynamics are studied. Results show that the frequency and the magnitude of the peak response increase with the increase of load. As the bearing clearance increases, the amplitude of the dominant mesh frequency is significantly increased. Under lower speed, the clearance has a limited effect on the dynamic mesh force. However, under moderate and high speeds, the main peak response frequency of the dynamic mesh force is decreased as it increases.
17
Content available Investigations of dynamic phenomena of precision length measurement system
Svilainis Paulius, Kavaliauskas Vilius, Kilikevičius Artūras, Matijošius Jonas, Więckowski Dariusz
Archiwum Motoryzacji
|
2020
|
Vol. 89, nr 3
51--59
EN
The development of the automotive industry is conditioned by the application of production technologies, which directly depend on production volumes. Today's development of car production is possible only in conjunction with the volume of production, ensuring both the parameters of assembly and production quality. Their constant monitoring is related to the application of the verification tools and technologies used. Such is the length measurement process that needs to be precise in the automotive industry. The paper analyzes the precision length measurement system and its dynamic characteristics. The research is applied to solve the problems of dynamic processes of a precision length measuring system, and the obtained results can be used in the development of precision systems for other purposes. The obtained results describe the vibrations of the length measuring system housing and the measuring head, which show the weak points of the system at the respective frequencies. The paper analyzes the precision length measurement system and its dynamic characteristics. The obtained results describe the vibrations of the length measuring system housing and the measuring head, which show the weak points of the system at the respective frequencies.
18
Content available Experimental study of precision angle encoder
Uvarovas Povilas, Kavaliauskas Vilius, Kilikevičienė Kristina, Kilikevičius Artūras, Svilainis Paulius, Matijošius Jonas, Więckowski Dariusz
Archiwum Motoryzacji
|
2020
|
Vol. 90, nr 4
5--14
EN
The application of new and advanced production processes plays an important role in the development of the manufacturing industry. This trend is especially relevant to the automotive industry, where each element must ensure high quality requirements. Therefore, automating the automotive manufacturing process is necessary to ensure the highest level of control methods. For this purpose, various sensors are used, the signals of which are analyzed and the control plan itself is adjusted. Experimental investigations of a precision angle encoder were performed in the work. During the research, the dynamic characteristics of the created stand were determined. Experimental studies yielded the results of an experimental study of a precision angle encoder when the system is subjected to shock and harmonic excitation. In order to elucidate the effect of oscillations on the accuracy of a high-resolution coded precision angle encoder, primary electrical signals and their change under oscillations were recorded. Studies have shown that high-resolution code-precision angle encoders have different design responses to dynamic effects depending on the direction of the vibrations acting.
19
Content available Investigation of the Dynamic Characteristics and Machining Stability of a Bi-rotary Milling Tool
Hung Jui-Pin, Lin Wei-Zhu
Advances in Science and Technology. Research Journal
|
2019
|
Vol. 13, no 1
14--22
EN
Bi-rotary milling head is the primary component of multiple-axis machine tool toward the multiply machining operation. The machining performance is greatly related to the structure characteristics and positioning precisions of the swivel head. This study was aimed at developing a bi-rotary milling head module, which is composed of a direct drive motor, cross roller bearings and motorized spindle unit. In order to evaluate the machining stability at the design phase, the dynamic characteristics of the rotary milling were first analyzed with finite element method. Especially, the variations of the dynamic characteristics of the spindle tool with the changing of the titling configuration of swivel axis were examined. In order to consider the accurate presentation of a spindle tool system and swivel mechanism, the bearings in the rolling components were also included in the finite element model and simulated with surface contact elements with adequate contact stiffness. The dynamic frequency response function of the spindle tool at different swinging positions were predicted for comparisons, which were further used to calculate the machining stability based on the machining mechanics. The current results show that the feeding direction and swinging positions of rotary milling head have a significant influence on the dynamic characteristics and machining ability of the spindle tool. The variations of the cutting depth with the swinging of A axis fall in the range of 11% to 40%, depending on the feeding direction and swinging angle. The analysis results are expected to clearly demonstrate the variation of the machining performance of the spindle tool under different milling configurations. The devised model and modeling approach can be applied to develop a five axis milling machine with desired dynamic and machining performance.
20
Content available Dynamic characteristics and stability of high speed cylindrical journal bearing
Strzelecki S.
Vibrations in Physical Systems
|
2018
|
Vol. 29
art. no. 2018025
EN
The operation of plain circular journal bearing at high speed is restricted by the excessive temperature that is generated in the oil film and by the loss of stability. Low costs of machining, high-transmitted loads are the advantages of these types of bearings. Better knowledge of bearing operation and its stability from the point of hydrodynamic theory of lubrication and theory of vibration can be affected by modifications of bearing design. These modifications should result in the higher speeds of operation, decrease in power losses and better bearing stability. The basis of stability determination is the dynamic characteristics of bearing. For the plain circular journal bearing the dynamic characteristics has been calculated. Stability of high speed, symmetric rotor was determined, too. Different values of bearing length to diameter ratio, and relative clearance were assumed. Reynolds', energy and viscosity equations were solved by means of iterative procedure. Adiabatic oil film, laminar flow in the bearing gap as well as aligned orientation of journal in the bearing was considered.
first rewind previous Strona / 4 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.