PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników
Powiadomienia systemowe
  • Sesja wygasła!
  • Sesja wygasła!

Znaleziono wyników: 11

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  wolne wibracje
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Transient analysis of transversely functionally graded Timoshenko beam (TFGTB) in conjunction with finite element method
Khafaji Salwan Obaid Waheed, Al-Shujairi Mohammed A., Aubad Mohammed Jawad
Archive of Mechanical Engineering
|
2020
|
LXVII, nr 3
299--321
EN
In this work, transient and free vibration analyses are illustrated for a functionally graded Timoshenko beam (FGM) using finite element method. The governing equilibrium equations and boundary conditions (B-Cs) are derived according to the principle of Hamilton. The materials constituents of the FG beam that vary smoothly along the thickness of the beam (along beam thickness) are evaluated using the rule of mixture method. Power law index, slenderness ratio, modulus of elasticity ratio, and boundary conditions effect of the cantilever and simply supported beams on the dynamic response of the beam are studied. Moreover, the influence of mass distribution and continuous stiffness of the FGM beam are deeply investigated. Comparisons between the current free vibration results (fundamental frequency) and other available studies are performed to check the formulation of the current mathematical model. Good results have been obtained. A significant effect is noticed in the transient response of both simply supported and cantilever beams at the smaller values of the power index and the modulus elasticity ratio.
2
Content available Dynamic behaviour of axially functionally graded beam resting on variable elastic foundation
Kumar Saurabh
Archive of Mechanical Engineering
|
2020
|
LXVII, nr 4
451--470
EN
In this paper, a comprehensive study is carried out on the dynamic behaviour of Euler–Bernoulli and Timoshenko beams resting on Winkler type variable elastic foundation. The material properties of the beam and the stiffness of the foundation are considered to be varying along the length direction. The free vibration problem is formulated using Rayleigh-Ritz method and Hamilton’s principle is applied to generate the governing equations. The results are presented as non-dimensional natural frequencies for different material gradation models and different foundation stiffness variation models. Two distinct boundary conditions viz., clamped-clamped and simply supported-simply supported are considered in the analysis. The results are validated with existing literature and excellent agreement is observed between the results.
3
Content available Shape optimization of a column under generalized load with a force directed towards positive pole
Szmidla Janusz, Jurczyńska Anna
Quality Production Improvement - QPI
|
2019
|
Vol. 1, Iss. 1
326--333
EN
In this paper, the issue of shape optimization of a column subjected to the generalized load with a force directed towards the positive pole (L. Tomski’s load, specific load) was considered. Based on the Hamilton’s principle, the differential equations of movement and boundary conditions describing the system were formulated. Taking into account a kinetic criterion of stability loss and a condition of constant total volume, the scope of changes in natural frequency as a function of an external load was determined with selected geometrical and physical parameters of the loading structure. On the basis of obtained results, values of geometrical parameters of individual column segments were determined, at which the maximum critical load value was obtained. In order to find the maximum critical force, which is a function of many variables, the simulated annealing algorithm was used.
4
Content available Efficient numerical modeling of functionally graded shell mechanical behavior
Koubaa Sana, Mars Jamel, Dammak Fakhreddine
Applied Computer Science
|
2019
|
Vol. 15, no 1
84--94
EN
Numerical analysis of the static bending and free vibration mechanical behavior of FGM are performed using the UMAT-USDFLD subroutines in ABAQUS software. Different combinations of geometries, mechanical loading and boundary conditions are adopted. The material properties according to the coordinates of the integration points are defined in the developed numerical model. The First Order Deformation Theory is used for thin and moderately thick FG shells analysis. The accuracy and the robustness of the numerical model are illustrated through the solution of several non trivial structure problems. The proposed numerical procedure is significantly efficient from the computational point of view.
5
Content available Natural transverse vibrations of helical springs in sections covered with elastic coatings
Michalczyk K.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2017
|
Vol. 65, nr 6
949--959
EN
It has been demonstrated in previous studies that local elastomer coatings covering the end coils of helical springs can efficiently reduce the amplitudes of circum-resonant vibrations in such springs. The analysis of the influence that elastic coatings have on the frequencies and modes of natural transverse vibrations of springs is presented in this paper. The concept of the equivalent beam of the Timoshenko type is utilized in calculations of the frequencies and modes of transverse vibrations. The model developed allows users to determine the frequencies and modes of symmetric as well as antisymmetric vibrations of axially loaded springs with elastic coatings of arbitrary length. A comparison of the results obtained using FEM analysis, in which the model represented the actual spring geometry, with the results obtained by means of the presented model indicates its high accuracy.
6
Content available Vibration analysis of composite circular and annular membranes
Siedlecka U., Zamorska I., Kukla S.
Journal of Applied Mathematics and Computational Mechanics
|
2016
|
Vol. 15, nr 1
149--159
EN
In this paper a solution to the free vibration problem of composite circular and annular membranes is presented. The vibrations of membranes whose material densities and/or thicknesses varied step-wise with the radial co-ordinate are considered. This approach is applied to approximate the solution to the vibration problem of a membrane with continuously varying density and/or thickness with the radial co-ordinate. The obtained analytical solutions are used in numerical investigations into the effect of parameters characterizing the composite membranes on their eigenfrequencies.
7
Content available Green’s function approach to frequency analysis of thin circular plates
Żur K. K.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2016
|
Vol. 64, nr 1
181--188
EN
The free vibration analysis of homogeneous and isotropic circular thin plates by using the Green’s functions is considered. The formulae for construction of the influence function for all nodal diameters are presented in a closed form. The limited independent solutions of differential Euler equations were expanded in the Neumann power series using the method of successive approximation. This approach allows to obtain the analytical frequency equations as power series rapidly convergent to exact eigenvalues for different number of nodal diameters. The first ten dimensionless frequencies for eight different natural modes of circular plates are calculated. A part of obtained results have not been presented yet in open literature for thin circular plates. The results of investigation are in good agreement with selected results obtained by other methods presented in literature.
8
Content available Finite element studies on free vibration of laminated composite cylindrical skew panels
Srinivasa C. V., Suresh Y. J., Prema Kumar W. P.
International Journal of Applied Mechanics and Engineering
|
2014
|
Vol. 19, no. 1
165--180
EN
This paper presents the finite element studies on free vibration of isotropic and laminated composite cylindrical skew panels. The analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN. The effects of the panel angle, skew angle, aspect ratio and length-to-thickness-ratio on fundamental frequency of isotropic cylindrical skew panels are studied. The effects of additional parameters such as the fiber orientation angle, numbers of layers and stacking sequence on the fundamental frequency of antisymmetric composite laminates are also studied. It is found that the CQUAD8 element yields better results than the CQUAD4 element in the validation and convergence studies. The CQUAD8 element is employed for the remaining part of the studies. The fundamental frequencies are found to increase with the panel angle and skew angle. When the number of layers in the laminate is large, the variation of the fundamental frequency with the number of layers is not appreciable. The boundary conditions are found to have a significant influence on the fundamental frequency.
9
Content available Free Vibration of Piezo-Nanowires Using Timoshenko Beam Theory with Consideration of Surface and Small Scale Effects
Oveisi A
Archive of Mechanical Engineering
|
2014
|
Vol. LXI, nr 1
139--152
EN
This paper investigates the influence of surface effects on free transverse vibration of piezoelectric nanowires (NWs). The dynamic model of the NW is tackled using nonlocal Timoshenko beam theory. By implementing this theory with consideration of both non-local effect and surface effect under simply support boundary condition, the natural frequencies of the NW are calculated. Also, a closed form solution is obtained in order to calculate fundamental buckling voltage. Finally, the effect of small scale effect on residual surface tension and critical electric potential is explored. The results can help to design piezo-NW based instruments.
PL
W pracy badano wpływ efektów powierzchniowych na poprzeczne drgania swobodne nanodrutów piezoelektrycznych (nanowires, NW). Model dynamiczny NW stworzono posługując sie nielokalna teoria belki Timoszenki. Stosując te teorie, przy uwzględnieniu zarówno efektów powierzchniowych i efektów nielokalnych, obliczono częstotliwości drgań własnych nanodrutu. Uzyskane rozwiązanie, o formie zamkniętej, pozwala także obliczyć podstawowe napięcie wyboczenia. Ponadto, zbadano wpływ efektów małej skali na resztkowe naprężenie powierzchniowe i potencjał elektryczny. Wyniki pracy mogą być użyteczne przy projektowaniu przyrządów wykorzystujących nanodruty piezoelektryczne.
10
Content available remote Natural vibration frequencies of tapered beams
Rosa de M. A., Lipiello M.
Engineering Transactions
|
2009
|
Vol. 57, iss. 1
45-66
EN
In this paper the free vibrations frequencies of tapered Euler-Bernoulli beams are calcu-lated, in the presence of an arbitrary number of rotationally and/or axially, elastically flexible constraints. The dynamic analysis is performed by means of the so-called cell discretization method (CDM), according to which the beam is reduced to a set of rigid bars, linked together by elastic sections, where the bending si iffness and the distributed mass of the bars is concentrated. The resulting stiffness matrix and mass matrix are easily deduced, and the generalized symmetric eingenvalue problem can be immediately solved. Various numerical comparisons allow us to show the potentialities of the proposed approach.
11
A study of the SU-22 structure for strength analysis, aerodynamics investigations, flight mechanics and free vibrations
Olejnik A., Kachel S., Leszczyński P., Jarzębiński L.
Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics
|
2001
|
nr 12
25-34
EN
In the paper a comprehensive method for the reconstruction of the existing aviation structures in a virtual reality is presented. The elaborated techniques can be applied to assessment of the ageing fleet of fixed as well as rotary wing aircraft used by the Polish Air Force. The Russian-made Su-22, the prime attack aircraft of the PAF was selected as a sample for strength evaluations. Generally speaking, it was a very difficult and complex task, because the PAF doesn't have a complete technical documentation and maintenance depot or overhaul technology of the considered aircraft.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.