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  1. 3 Computer Assisted Mechanics and Engineering Sciences
  2. 3 Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska
  3. 2 Przegląd Budowlany
  4. 2 Scientific Letters of Rzeszow University of Technology. Mechanics
  5. 2 Vibrations in Physical Systems
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  1. 3 Musiał M.
  2. 2 Bozduganova V.
  3. 2 Todorov M.
  4. 1 Aslanyan A. G.
  5. 1 Banaś A.
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  1. 1 2019
  2. 1 2017
  3. 1 2016
  4. 3 2015
  5. 1 2014
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1
Content available remote Implementation of dual-frequency resonant vibratory machines with pulsed electromagnetic drive
Gursky Volodymyr M., Kuzio Igor V., Lanets Oleksiy S., Tolegenova Akmaral, Syzdykpayeva Aigul
Przegląd Elektrotechniczny
|
2019
|
R. 95, nr 4
41--46
EN
The rational method of implementation of dual-frequency resonant systems with multiple eigenfrequencies of oscillations is considered. The efficiency of implementation of such operation modes is substantiated by the use of a pulsed electromagnetic drive with oscillations frequency of 50 Hz. The analysis of the vibrating system dynamics is carried out on the basis of numerical modelling of the system of nonlinear ordinary differential equations. The influence of inertia of auxiliary oscillating mass on the indexes of acceleration of the working device, namely on its maximum value and on the fundamental harmonics ratio, is investigated. The structure of a partial module, which is a means of modernization of single-frequency resonant systems, is proposed.
PL
Rozważana jest racjonalna metoda implementacji systemów rezonansowych o dwóch częstotliwościach z wieloma częstotliwościami drgań własnych. Efektywność realizacji takich trybów pracy jest uzasadniona przez zastosowanie impulsowego napędu elektromagnetycznego o częstotliwości drgań 50 Hz. Analiza dynamiki układu wibracyjnego przeprowadzana jest na podstawie numerycznego modelowania układu nieliniowych równań różniczkowych zwyczajnych. Zbadano wpływ bezwładności pomocniczej masy oscylacyjnej na wskaźniki przyspieszenia urządzenia roboczego, a mianowicie na jej wartość maksymalną i na współczynnik podstawowej harmonicznej. Zaproponowano strukturę modułu częściowego, który jest środkiem do modernizacji układów rezonansowych o jednej częstotliwości.
2
Content available Dynamic analysis of optimized two-phase auxetic structure
Idczak E., Stręk T.
Vibrations in Physical Systems
|
2017
|
Vol. 28
art. no. 2017003
EN
This paper presents a dynamic analysis of earlier optimized auxetic structure. This optimization based on the distribution of two materials in such way to obtain a minimal value of Poisson’s ratio (PR), which indicates the auxetic properties. The initial optimized shape was so-called star structure, which if is made from one material has the PR close to 0.188. After optimization with the goal function of PR-minimization, the obtained value was equal to -9.5043. Then the eigenfrequencies for the optimized structure were investigated. The calculations were carried out by means of Finite Element Method (FEM). For optimization of the value of Poisson’s ratio was used algorithm MMA (Method of Moving Asymptotes). The computing of single material properties (PR, Young’s modulus, density) for the whole shape was made by means of SIMP method (Solid Isotropic Method with Penalization).
3
Content available remote Badanie doświadczalne częstotliwości własnych i ugięć belek żelbetowych wzmocnionych taśmami CFRP
Musiał M.
Materiały Budowlane
|
2016
|
nr 9
68--69
PL
W artykule przedstawiono wyniki badań doświadczalnych belek żelbetowych wzmocnionych taśmami CFRP. Niewzmocnione belki obciążano wstępnie do 80% nośności, a następnie wzmacniano je od zewnątrz taśmami CFRP i obciążono do ich zniszczenia. W czasie badań mierzono częstotliwości własne i ugięcia belek. Stwierdzono, że taśmy kompozytowe zahamowały spadek częstotliwości własnych w wyniku obciążania, jaki ma miejsce w przypadku belek niewzmocnionych.
EN
In the paper experimental studies on reinforced concrete beams strengthened with CFRP strips are described. Unstrengthened beams were loaded initially to 80% of load capacity, and then external CFRP strengthening was applied. Strengthened beams were loaded till their failure. During the tests eigenfrequencies and deflections of beams were measured. It was observed that composite stripes had inhibited the decrease of eigenfrequencies as a consequence of loading, which occurs in case of unstrengthened beams.
4
Content available Wyznaczanie częstości drgań własnych łuków z wykorzystaniem sztucznych sieci neuronowych
Kaczmarek M.
Przegląd Budowlany
|
2015
|
R. 86, nr 12
52--55
PL
Analiza zagadnienia własnego, czyli częstości i postaci drgań własnych, prętów zakrzywionych stanowi tematykę interesującą wielu badaczy. Zagadnienie drgań łuków jest istotnym problemem z uwagi na zastosowanie tych układów w budownictwie i mechanice.
EN
The analysis of free transverse vibration frequency of the curves curved rods has been a subject of interest for numerous researchers. The issue of the vibration of the curves is a major problem due to the use of the aforesaid technology in construction and mechanics.
5
Content available Analizy dynamiczne w projektowaniu kładek dla pieszych
Pańtak M.
Przegląd Budowlany
|
2015
|
R. 86, nr 6
78--82
PL
W artykule przedstawiono zagadnienie analiz dynamicznych kładek dla pieszych narażonych na dynamiczne oddziaływania użytkowników. Scharakteryzowane zostały poszczególne etapy analizy obejmujące ustalenie krytycznego przedziału częstotliwości drgań własnych konstrukcji oraz częstotliwości oddziaływań jej użytkowników, modelowanie oddziaływań pieszych oraz ocenę komfortu użytkowania konstrukcji. Przedstawiono modele oddziaływań pieszych na konstrukcje w postaci chodu, biegu i skoków oraz charakterystykę podstawowych parametrów dynamicznych konstrukcji.
EN
In the paper the issue of dynamic analysis of the footbridges subjected to dynamic action of the users has been presented. The various stages of the analysis involves the determination of the critical range of the natural frequency of the structure and the frequency of dynamic actions of the users, mathematical models of the dynamic action of the users and the assessment of the comfort of use of the structure have been characterized. The mathematical models of the dynamic actions of the users on structures in the form of walking, running and jumping and basic dynamic parameters of the structure have been described.
6
Content available remote Young’s modulus test in two directions on the basis of eigenfrequencies in concrete beams
Musiał M.
Czasopismo Techniczne. Budownictwo
|
2015
|
Y. 112, iss. 3-B
133--142
EN
This paper covers the experimental studies of Young’s modulus of concrete on the basis of eigenfrequencies. Experiments were performed on beam elements measuring 1050×200×100 mm, using operational modal analysis (OMA). Two types of concrete with different mixtures were tested. The dynamic Young’s modules were calculated on the basis on the resonant frequencies measured in two directions. The values obtained were compared with static Young’s modules determined on concrete cylinders in axial compression testing.
PL
W artykule zrelacjonowano badania eksperymentalne modułu Younga betonu na podstawie częstotliwości własnych. Eksperymenty przeprowadzono na elementach belkowych o wymiarach 1050×200×100 mm z wykorzystaniem operacyjnej analizy modalnej (OMA). Przebadano dwa betony o różnych recepturach. Dynamiczne moduły Younga obliczono na podstawie pomierzonych w dwóch kierunkach częstotliwości własnych. Uzyskane wartości porównano ze statycznymi modułami Younga określonymi na betonowych walcach w próbie osiowego ściskania.
7
Content available remote The influence of fill factor on the phononic crystal eigenfrequencies
Gruszka K., Nabiałek M., Szota M.
Archives of Materials Science and Engineering
|
2014
|
Vol. 66, nr 2
74--80
EN
Purpose: The aim of this article is to determine the effect of basic cell fill factor change on the eigenfrequencies observed in two-dimensional phononic crystal. Design/methodology/approach: To perform simulation, the FDFD (finite difference frequency domain) algorithm was used. On this basis, the search for eigenfrequencies was carried out starting from lowest possible acoustic frequency range (~20 Hz) and limited to first nine search results found (up to nearly 2.2 kHz) for increasing fill factor while maintaining the shape of a rod inside cell. Findings: The fill factor has a significant influence on the eigenfrequencies of the studied system when the frequency is above 1 kHz. With the increase of this factor at relatively low frequencies (less than 1 kHz in this case) there were no major changes observed. Research limitations/implications: The results were found only for specific system consisting of materials with similar sound velocity. Therefore, more research should be carried out for other cases i.e. taking into account the different topology of primary cells and various materials with other propagation velocity of acoustic waves in these mediums. Practical implications: Simulation of two-dimensional phononic crystal systems allows for designing new specialized multi-component materials with various acoustic properties. These systems can be adapted in a variety of applications, including acoustic filters, slow-wave devices, acoustic autocollimators and many other. Originality/value: Basic research allow to improve the quality of knowledge on more advanced problems. For this reason, it is important to know in detail how simple systems work and to determine the basic properties of these systems.
8
Content available remote Free Vibrations of Carbon Nanotubes with Defects
Muc A., Banaś A., Chwał A.
Mechanics and Mechanical Engineering
|
2013
|
Vol. 17, nr 2
157--166
EN
In the paper the eigenfrequencies of pristine and defective single-walled carbon nanotubes are investigated. The defects are in the form of point vacancies. The axial vibrations of structures are studied only. A special attention is focused on the effects of material and geometrical properties of nanostructures on the results. Three different models are considered: the Euler beam model, a continuous specially orthotropic model and a 3D nonlinear finite element model consistent with molecular mechanics formulations. The results demonstrate that the Euler beam model overestimates the values of natural frequencies.
9
Content available remote Eigenfrequencies determination by hybrid stress finite element method
Bozduganova V., Todorov M.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
|
2010
|
z. 80 [274]
33-38
EN
An application of hybrid stress method in studying the free vibrations of two-dimensional continuum in plane stress or plane strain problems by finite elements is investigated. The basis of the method is the assumed parametric stress field giving equilibrium of the internal forces inside the element area. The displacements on the element boundary are independent of the stress field and fully determined by the nodal displacements. The displacement field inside the element is independent of the assumed stress field and it is determined by parameters different than the assumed stress field parameters. Differentiating the assumed displacement field, a new stress field is obtained, which parameters are set to approach the assumed stress field by the least squares method.
10
Content available remote Computation of plane structures eigenfrequencies by hybrid finite element method using Trefftz functions
Bozduganova V., Todorov M.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
|
2010
|
z. 80 [274]
25-32
EN
A hybrid stress method for eigenfrequencies analysis is developed using a plane rectangular hybrid element. Complex Trefftz functions which are solutions of elastostatic problem are used. By the complementary energy variational equation a relationship between the stress parameters and the nodal displacements is obtained. The Lagrange's variational equation for the dynamic case gives an expression for computation of eigenfrequencies.
11
Badania doświadczalne wpływu historii obciążenia na częstotliwości drgań własnych belki żelbetowej
Grosel J., Musiał M., Ubysz A., Wójcicki Z.
Inżynieria i Budownictwo
|
2010
|
R. 66, nr 12
714-715
PL
W zginanych elementach żelbetowych rysy wpływają na zmianę dynamicznych parametrów konstrukcji. Badania doświadczalne historii obciążenia i operacyjna analiza modalna drgającej belki pozwalają przewidzieć zmiany tych parametrów. Opisano operacyjną analizę modalną. Przedstawiono metodę badań eksperymentalnych i wybrane wyniki tych badań.
EN
The cracks in bending reinforced concrete beams change some dynamical parameters of constructions. The experimental research of load history and operational modal analysis of the vibrating beams allow this changes to expect. In the first part of this paper the operational modal analysis is described. The method of experimental research and the chosen results are in the second part shown.
12
Content available remote Maximal frequency, amplitude, kinetic energy and elbow joint stiffness in cyclic movements
Zawadzki J., Siemieński A.
Acta of Bioengineering and Biomechanics
|
2010
|
Vol. 12, no. 2
55-64
EN
The present work deals with those properties of the human motor system that characterize cyclic movements of maximum (expected to be maximum) intensity. It presents the results of an experiment carried out on 11 subjects and aimed at measuring the kinematic characteristics of cyclic movements of the elbow joint executed at maximal frequency under unloaded conditions. The movements of five amplitude levels ranging from 0.1 rad to approximately 1.2 rad were considered. An observable and unequivocal relation was found between the amplitude and the maximal movement frequency. The said relation is one of an inverse relationship types described by the equation of a shifted hyperbola intersecting the frequency axis at a point marking the value of maximal movement frequency fmax whose mean value was 8.42 Hz in the group investigated. It was also established that elbow joint movements executed at maximal intensity show significant similarity to harmonic movement, which points to the “stiff” characteristic of useful driving torque. Relationships between maximal amplitudes of angular velocity, angular acceleration, kinetic energy and movement amplitude were also determined. The nature of the said relationships derives from the superposition of the two abovementioned features – the amplitude–frequency relation and the formal relationships between the values describing harmonic movement. The elbow joint stiffness manifested during cyclic movements appears to be related to both movement frequency and amplitude. Its value increases with frequency and decreases with amplitude growth ranging from approximately 15 to 130 Nm/rad. The source of the said stiffness is to be found in the properties of the tendon–muscle complex and its changes depend on the changes of muscle tension. This feature has been illustrated by the measurement of the relation between elbow joint stiffness and the static torque generated by elbow joint flexors and extensors. It has been established that the stiffness increases with muscle tension squared.
13
Content available remote Interval and fuzzy eigenfrequency analysis of uncertain substructured FE models
De Gersem H., Moens D., Desmet W., Vandepitte D.
Computer Assisted Mechanics and Engineering Sciences
|
2007
|
Vol. 14, No. 2
167-181
EN
This paper uses an interval and fuzzy finite element approach for the eigenfrequency analysis of a mechanical structure with uncertain parameters. The component mode synthesis method is applied for the numerical reduction of the structure, in order to reduce the calculation time of the interval and fuzzy analyses. Special attention is paid to the effect of uncertainties on the description of the substructuring technique and the consequences on the calculation time. All concepts are illustrated through a benchmark structure example.
14
Alternatywne metody diagnozowania stanu połączeń biomechanicznych
Nowak B., Najar J.
Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska
|
2006
|
z. 30
211-218
PL
W pracy przedstawiono przykład formułowania metody badania stanu połączeń biomechanicznych na podstawie analizy modalnej i przy wykorzystaniu metody elementów skończonych. W analizie wstępnej użyto elementarnych modeli belkowych. Analizie i dyskusji poddano wpływ niespójności struktury na częstotliwości i postacie własne drgań a także na przemieszczenia wybranych punktów pod wpływem periodycznych wymuszeń o zadanych częstotliwościach.
EN
An example of problem formulation for diagnosing the state of fixation in biomaterials has been presented on the basis of modal analysis and finite element method used in computations. In primary analysis fixation is modeled with two beam elements. Eigenfrequencies, modeshapes and displacements of chosen points were calculated. The influence of the fixation length for their values was discussed.
15
Content available remote Vibrations of a weakly nondegenerate 1D-3D multi-structure
Aslanyan A. G., Dronka J., Mishuris G., Selsil O.
Archives of Mechanics
|
2006
|
Vol. 58, nr 1
17-43
EN
We study the effect of the transition between degenerate and nondegenerate configurations for a 1D-3D multi-structure, by considering a particular nondegenerate configuration. Analytical asymptotic formulae are derived for the first six eigenfrequencies which include information about the location of the 1D parts (legs) of the multi-structure. This enables us to analyse the transition region by moving the legs closer to each other. Accuracy of the asymptotic formulae is compared with numerical solution for the pile structure (skeleton) and with finite element computations. Some inaccuracies associated with numerical and finite element computations are discussed. In addition, a discussion on two-sided estimates for the eigenfrequencies is also included.
16
Content available remote Identification of Crack in Beams Using Eigenfrequency
Majkut L.
Vibrations in Physical Systems
|
2004
|
Vol. 21
251--254
17
Content available remote Częstości drgań belki Timoshenki z uwzględnieniem nieliniowego podłoża
Bar O.
Czasopismo Techniczne. Mechanika
|
2004
|
R. 101, z. 13-M
3--13
PL
Celem pracy jest porównanie numerycznej metody wyznaczania częstości drgań belki Timoshenki z metodą analityczną przy uwzględnieniu dwuparametrowego, nieliniowego podłoża. Przebadano także wpływ parametrów układu oraz warunków początkowych na postać drgań.
EN
The aim of this work is to compare numerical method calculation of frequency of the Timoshenko beam with the analytical method taking into consideration two-parametrical, nonlinear basis. The influence of the characteristics of the system on the shape of the vibration was also researched.
18
Condensation of substructures using modal synthesis method
Sikora R.
Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska
|
2002
|
z. 19
139-142
EN
Condensation methods are used for calculations of structural eigenvectors and eigenfrequencies provided that characteristics of individual substructures and couplings between nodes are known. There is described verification of the method as exemplified by conservative structure in this article. Two beams and springs between them form this structure.
19
Content available remote Wpływ masy czujnika na pomiar drgań własnych płyty kołowej utwierdzonej na obwodzie
Jaroszewicz J., Jermołaj M., Ostapkowicz P., Łapiński R.
Zeszyty Naukowe Politechniki Białostockiej. Budowa i Eksploatacja Maszyn
|
2001
|
Z. 8
171-190
PL
W pracy przedstawiono stanowisko badawcze do wyznaczania doświadczalnych wartości częstości drgań własnych wykorzystując metodę impulsową i metodę wymuszenia harmonicznego, dla przyjętego modelu, tj. płyty kołowej, utwierdzonej na obwodzie z masą skupioną w jej środku. Wyznaczono charakterystyki amplitudowo-częstotliwościowe płyty z masą skupioną. Do obliczeń teoretycznych kolejnych trzech częstotliwości osiowosymetrycznych drgań własnych wykorzystano metodę funkcji Bessela i metodę szeregów charakterystycznych. Ponadto przedstawiono obliczenia częstości i postaci drgań własnych płyty metodą elementów skończonych (MES), na podstawie aplikacji MSC/Patran oraz MSC/Nastran. Wykazano, że obliczenie częstotliwości drgań przy pomocy MES jest obarczone najmniejszym błędem.
EN
Aim of paper is examining of influence of mass of sensor, as additional collected masses, on frequency of axial - symmetrical vibrations of circular plate. One introduced investigative position to marking experimental values of frequency of free vibrations using method impulse and extortion's harmonic, for accepted model, i.e. circular plates, fixed on circumference with collected mass in her centre. One-marked characterisations of amplitude - frequency of plate with collected mass. To theoretical calculations following three frequencies axial - symmetrical of free vibrations one used method of function Bessela and method of characteristic rows. Besides one made calcula- tions of frequency and of form of natural oscillations of plate with method of finite elements of (MESSES), basing on applications MSC/PATRAN and MSC/NASTRAN. One-showed, that a calculation of frequency of vibrations at help of MESSES is burdened least error.
20
Content available remote Efficient free vibration analysis of large structures with close or multiple natural frequencies. P. 2 : Damped structures
Lee I. W., Jung H. J., Kim M. Ch.
Computer Assisted Mechanics and Engineering Sciences
|
1999
|
Vol. 6, No. 3-4
415-424
EN
An efficient solution method is presented to solve the eigenvalue problem arising in the dynamic analysis of nonproportionally damped structural systems with close or multiple eigenvalues. The proposed method is obtained by applying the modified Newton-Raphson technique and the orthonormal condition of the eigenvectors to the linear eigenproblem format through matrix augmentation of the quadratic eigenvalue problem. In the iteration methods such as the inverse iteration method and the subspace iteration method, singularity may be occurred during the factorizing process when the shift value is close to an eigenvalue of the system. However, even if the shift value is an eigenvalue of the system, the proposed method guarantees nonsingularity, which is analytically proved. The initial values of the proposed method can be taken as the intermediate results of iteration methods or results of approximate methods. Two numerical examples are also presented to demonstrate the effectiveness of the proposed method and the results are compared with those of the well-known subspace iteration method and the Lanczos method.
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