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Wyświetlanie 1-15 z 17
Tytuł:
Multiscale Approach for Modeling Fracture in Piezoelectric Ceramics
Autorzy:
Biglar, M.
Stachowicz, F.
Trzepieciński, T.
Gromada, M.
Powiązania:
https://bibliotekanauki.pl/articles/355254.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
barium titanate
BEM
boundary element method
ceramics
Opis:
The barium titanate material is the most intensively studied perovskite material due to its wide use in the ceramic industry. Barium titanate is also technologically important material owing to its ferroelectric behaviour at and above room temperature. The paper presents an effective implementation of boundary element multiscale method in analyzing of fracture of piezoelectric ceramics. This method can be easily used to get a better understanding of damage mechanism in the ceramic materials in order to improve the constitutive models and to support the future design of those materials. In this method the relation of boundary element method for obtaining traction is presented. The main advantage of boundary element method is the reduction of the dimensionality of the problem. Boundary element method becomes very attractive in cases of numerically complex problems that are computationally expensive.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 1; 22-28
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elongation determination using finite element and boundary element method
Autorzy:
Kisała, P.
Wójcik, W.
Smailov, N.
Kalizhanova, A.
Harasim, D.
Powiązania:
https://bibliotekanauki.pl/articles/226029.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
finite element method
boundary element method
fiber Bragg gratings
elongation distribution
Opis:
This paper presents an application of the finite element method and boundary element method to determine the distribution of the elongation. Computer simulations were performed using the computation of numerical algorithms according to a mathematical structure of the model and taking into account the values of all other elements of the fiber Bragg grating (FBG) sensor. Experimental studies were confirmed by elongation measurement system using one uniform FBG.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 389-394
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2D Structural Acoustic Analysis Using the FEM/FMBEM with Different Coupled Element Types
Autorzy:
Chen, L.
Zhao, W.
Liu, C.
Chen, H.
Powiązania:
https://bibliotekanauki.pl/articles/176330.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boundary element method
finite element method
discontinuous boundary elements
acoustic fluid-structure interaction
fast multipole method
Opis:
A FEM-BEM coupling approach is used for acoustic fluid-structure interaction analysis. The FEM is used to model the structure and the BEM is used to model the exterior acoustic domain. The aim of this work is to improve the computational efficiency and accuracy of the conventional FEM-BEM coupling approach. The fast multipole method (FMM) is applied to accelerating the matrix-vector products in BEM. The Burton-Miller formulation is used to overcome the fictitious eigen-frequency problem when using a single Helmholtz boundary integral equation for exterior acoustic problems. The continuous higher order boundary elements and discontinuous higher order boundary elements for 2D problem are developed in this work to achieve higher accuracy in the coupling analysis. The performance for coupled element types is compared via a simple example with analytical solution, and the optimal element type is obtained. Numerical examples are presented to show the relative errors of different coupled element types.
Źródło:
Archives of Acoustics; 2017, 42, 1; 37-48
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Coupled Smoothed Finite Element-Boundary Element Method for Structural-Acoustic Analysis of Shell
Autorzy:
Tian, W.
Yao, L.
Li, L.
Powiązania:
https://bibliotekanauki.pl/articles/177260.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
SFEM
smoothed finite element method
FEM
finite element method
BEM
boundary element method
structural-acoustic analysis
Opis:
Nowadays, the finite element method (FEM) – boundary element method (BEM) is used to predict the performance of structural-acoustic problem, i.e. the frequency response analysis, modal analysis. The accuracy of conventional FEM/BEM for structural-acoustic problems strongly depends on the size of the mesh, element quality, etc. As element size gets greater and distortion gets severer, the deviation of high frequency problem is also clear. In order to improve the accuracy of structural-acoustic problem, a smoothed finite-element/boundary-element coupling procedure (SFEM/BEM) is extended to analyze the structural-acoustic problem consisting of a shell structure interacting with the cavity in this paper, in which the SFEM and boundary element method (BEM) models are used to simulate the structure and the fluid, respectively. The governing equations of the structural-acoustic problems are established by coupling the SFEM for the structure and the BEM for the fluid. The solutions of SFEM are often found to be much more accurate than those of the FEM model. Based on its attractive features, it was decided in the present work to extend SFEM further for use in structural-acoustic analysis by coupling it with BEM, the present SFEM/BEM is implemented to predict the vehicle structure-acoustic frequency response analysis, and two numerical experiments results show that the present method can provide more accurate results compared with the standard FEM/BEM using the same mesh. It indicates that the present SFEM/BEM can be widely applied to solving many engineering noise, vibration and harshness (NVH) problems with more accurate solutions.
Źródło:
Archives of Acoustics; 2017, 42, 1; 49-59
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Boundary-integral model of permanent magnet of a tube segment as shape
Autorzy:
Pawluk, K.
Sulima, R.
Powiązania:
https://bibliotekanauki.pl/articles/140403.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnes trwały
metoda całkowo-brzegowa
całki eliptyczne
permanent magnets
boundary integral method
elliptic integrals
Opis:
The magnetic field due to a permanent magnet of a tube-side segment as shape and of radial-oriented magnetization is considered. Such a sheet modelling a single pole of the magnet is used to express the suitable contribution to magnetic quantities. A boundary-integral approach is applied that is based on a virtual scalar quantity attributed to the magnet pole. Such an approach leads to express analytically the scalar magnetic potential and the magnetic flux density by means of the elliptic integrals. Numerical examples of the computed fields are given. The general idea of the presented approach is mainly directed towards designing the magnetic field within the air gap of electric machines with permanent magnets as an excitation source. Other technical structures with permanent magnets may be a subject of this approach as well.
Źródło:
Archives of Electrical Engineering; 2011, 60, 4; 413-432
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wedge functions applied to 2D magnetostatic problems
Autorzy:
Huijer, E.
Karaki, S.H.
Powiązania:
https://bibliotekanauki.pl/articles/140344.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
klin
przenikalność magnetyczna
metoda całkowo-brzegowa
finite permeability
wedge functions
segment functions
boundary integral method
Opis:
In this paper the application of so called wedge functions is presented to solve two-dimensional simple geometries of magnetostatic and electrostatic problems, e.g. rectangles of varying aspect ratio and with different values of the magnetic permeability μ. Such problems require the use of surface charge density, or segment source, functions of the form ρs = σa-1, where the power parameters, a, have special fractional values. A methodology is presented to determine these special values of a and use them in segment sources on simple geometries, i.e. rectangles of varying aspect ratio, and with different values of the magnetic permeability μ. Wedge solutions are obtained by coupling the strength coefficients of source segments of the same power around an edge. These surface source functions have been used in the analysis of conducting and infinite permeability structures. Here we apply such functions in a boundary integral analysis method to problems having regions of finite permeability.
Źródło:
Archives of Electrical Engineering; 2011, 60, 4; 519-529
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On evaluation of influence coefficients for edge and intermediate boundary elements in 3D problems involving strong field concentrations
Autorzy:
Rybarska-Rusinek, L.
Powiązania:
https://bibliotekanauki.pl/articles/201139.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boundary integral equation
boundary element method
singular element
Hadamard finite part integral
brzegowe równanie całkowe
metoda elementów brzegowych
macierz Hadamarda
Opis:
The paper presents a tool for accurate evaluation of high field concentrations near singular lines, such as contours of cracks, notches and grains intersections, in 3D problems solved the BEM. Two types of boundary elements, accounting for singularities, are considered: (i) edge elements, which adjoin a singular line, and (ii) intermediate elements, which while not adjoining the line, are still under strong influence of the singularity. An efficient method to evaluate the influence coefficients and the field intensity factors is suggested for the both types of the elements. The method avoids time expensive numerical evaluation of singular and hypersingular integrals over the element surface by reduction to 1D integrals. The method being general, its details are explained by considering a representative examples for elasticity problems for a piecewise homogeneous medium with cracks, inclusions and pores. Numerical examples for plane elements illustrate the exposition. The method can be extended for curvilinear elements.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 1; 69-76
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape Optimisation of Multi-Chamber Acoustical Plenums Using BEM, Neural Networks, and GA Method
Autorzy:
Chang, Y.-C.
Cheng, H.-C.
Chiu, M.-C.
Chien, Y.-H.
Powiązania:
https://bibliotekanauki.pl/articles/177780.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boundary element method
plenum
centre-opening baffle
polynomial neural network model
group method of data handling
optimisation
genetic algorithm
Opis:
Research on plenums partitioned with multiple baffles in the industrial field has been exhaustive. Most researchers have explored noise reduction effects based on the transfer matrix method and the boundary element method. However, maximum noise reduction of a plenum within a constrained space, which frequently occurs in engineering problems, has been neglected. Therefore, the optimum design of multi-chamber plenums becomes essential. In this paper, two kinds of multi-chamber plenums (Case I: a two-chamber plenum that is partitioned with a centre-opening baffle; Case II: a three-chamber plenum that is partitioned with two centre-opening baffles) within a fixed space are assessed. In order to speed up the assessment of optimal plenums hybridized with multiple partitioned baffles, a simplified objective function (OBJ) is established by linking the boundary element model (BEM, developed using SYSNOISE) with a polynomial neural network fit with a series of real data – input design data (baffle dimensions) and output data approximated by BEM data in advance. To assess optimal plenums, a genetic algorithm (GA) is applied. The results reveal that the maximum value of the transmission loss (TL) can be improved at the desired frequencies. Consequently, the algorithm proposed in this study can provide an efficient way to develop optimal multi-chamber plenums for industry.
Źródło:
Archives of Acoustics; 2016, 41, 1; 43-53
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A meshless method for subsonic stall flutter analysis of turbomachinery 3D blade cascade
Autorzy:
Prasad, Chandra Shekhar
Šnábl, Pavel
Pešek, Luděk
Powiązania:
https://bibliotekanauki.pl/articles/2090682.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stall flutter
turbomachinery cascades
reduce-order-model
meshless method
viscous-inviscid coupling
boundary element method
metoda bezsiatkowa
metoda elementów brzegowych
Opis:
The analysis of subsonic stall flutter in turbomachinery blade cascade is carried out using a medium-fidelity reduced-order aeroelastic numerical model. The model is a type of field mesh-free approach and based on a hybrid boundary element method. The medium-fidelity flow solver is developed on the principle of viscous-inviscid two-way weak-coupling approach. The hybrid flow solver is employed to model separated flow and stall flutter in the 3D blade cascade at subsonic speed. The aerodynamic damping coefficient w.r.t. inter blade phase angle in traveling-wave mode is estimated along with other parameters. The same stability parameter is used to analyze the cascade flutter resistance regime. The estimated results are validated against experimental measurements as well as Navier-Stokes based high fidelity CFD model. The simulated results show good agreement with experimental data. Furthermore, the hybrid flow solver has managed to bring down the computational cost significantly as compared to mesh-based CFD models. Therefore, all the prime objectives of the research have been successfully achieved.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 6; e139000, 1--9
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of nonlinear standing waves underneath a deck
Autorzy:
Majewski, D.
Sulisz, W.
Powiązania:
https://bibliotekanauki.pl/articles/1849771.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
uderzenie falii
impuls ciśnienia
budowla brzegowa
budowla morska
fala wodna
metoda elementów brzegowych
model numeryczny
wave impact
impact pressure
coastal structure
offshore structure
water wave
boundary element method
numerical model
Opis:
A theoretical approach was applied to investigate the impact of nonlinear standing waves underneath a horizontal deck. A solution was achieved by applying a boundary element method. The model was applied to predict impact pressure underneath a deck. The results show that the wave impact is a very complex momentary process. The influence of initial boundary conditions, wave parameters and deck clearance on impact pressure are analysed. The analysis shows that purely sinusoidal waves of very small amplitude may cause an impact pressure several orders of magnitude higher than a pressure arising from typical applications of a linear wave theory. The analysis shows that all these non-intuitive outcomes arise from the complexity of a wave impact process and its enormous sensitivity to initial conditions what indicates serious difficulties in a reliable prediction of a wave impact for complex wave fields or other structures. Laboratory experiments were conducted to validate theoretical results.
Zbadano proces uderzenia nieliniowych, stojących fal wodnych w spód poziomego pokładu. Wykorzystano podejście teoretyczne, którego rozwiązanie opiera się na Metodzie Elementów Brzegowych. Za pomocą modelu wyznaczono ciśnienia generowane uderzeniem fal wodnych. Wyniki wskazują na to, że proces jest bardzo złożony i ma charakter impulsowy. Analizowano wpływ początkowych warunków brzegowych, parametrów fali oraz wysokości zawieszenia pokładu nad powierzchnią spokoju na generowane ciśnienia. Wyniki pokazują, że nawet fale sinusoidalne, o małej amplitudzie mogą wywołać ciśnienia kilkukrotnie większe niż ciśnienia wynikające z typowych zastosowań teorii liniowej falowania. Pokazują również, że często nieintuicyjne wnioski wynikają ze złożoności procesu uderzenia fali i jego dużej czułości na początkowe warunki brzegowe. Wskazuje to na poważne trudności w wiarygodnym modelowaniu procesu uderzenia dla złożonych pól falowych oraz skomplikowanych układów geometrycznych budowli. Przeprowadzono również pomiary laboratoryjne w celu uzyskania danych do walidacji modelu numerycznego. Opracowany model zapewnia wyniki z dokładnością umożliwiającą zastosowanie go w zadaniach inżynierskich.
Źródło:
Archives of Civil Engineering; 2020, 66, 4; 79-96
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonsingular Meshless Method in an Acoustic Indoor Problem
Autorzy:
Brański, A.
Prędka, E.
Powiązania:
https://bibliotekanauki.pl/articles/177716.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
architectural acoustics
meshless method
radial bases functions
impedance boundary condition
Opis:
An efficiency of the nonsingular meshless method is analyzed in an acoustic indoor problem. The solution is assumed in the form of the series of radial bases functions. The Hardy’s multiquadratic functions, as the bases, are taken into account. The room acoustic field with uniform, impedance walls is considered. The representative, rectangular cross section of the room is chosen. Practical combinations of acoustic boundary conditions, expressed through absorption coefficient values, are considered. The classical formulation of the boundary problem is used. It is established any coefficient in the multiquadratic functions depend on the number of influence points, the frequency and the absorption coefficient. All approximate results are calculated in relation to the exact ones. This way, it is proved that the meshless method based on the multiquadratic functions is simple and efficient method in the description of the complicated acoustic boundary problems for the low and medium ranges of frequency.
Źródło:
Archives of Acoustics; 2018, 43, 1; 75-82
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recent simulation results of the magnetic induction tomography forward problem
Autorzy:
Stawicki, K.
Szuflitowska, B.
Ziolkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/141095.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boundary conditions
eddy current testing
finite element method
magnetic
induction tomography
Opis:
In this paper we present the results of simulations of the Magnetic Induction Tomography (MIT) forward problem. Two complementary calculation techniques have been implemented and coupled, namely: the finite element method (applied in commercial software Comsol Multiphysics) and the second, algebraic manipulations on basic relationships of electromagnetism in Matlab. The developed combination saves a lot of time and makes a better use of the available computer resources.
Źródło:
Archives of Electrical Engineering; 2016, 65, 2; 327-336
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal boundary control problems of retarded parabolic systems
Autorzy:
Kowalewski, A.
Krakowiak, A.
Powiązania:
https://bibliotekanauki.pl/articles/229191.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boundary control
parabolic systems
time delays
linear quadratic problem
quadratic programming method
Opis:
Optimal boundary control problems of retarded parabolic systems are presented. Necessary and sufficient conditions of optimality are derived for the Neumann problem. A simple example of application is also presented.
Źródło:
Archives of Control Sciences; 2013, 23, 3; 261-279
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Implementation of the Fictitious Domain Method for Elliptic Equations
Autorzy:
Temirbekov, A. N.
Wójcik, W.
Powiązania:
https://bibliotekanauki.pl/articles/226820.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
elliptic equation
Dirichlet problem
equation with rapidly varying coefficients
computational algorithm
iterative process
fictitious domain method
boundary conditions
Opis:
In this paper, we consider an elliptic equation with strongly varying coefficients. Interest in the study of these equations is connected with the fact that this type of equation is obtained when using the fictitious domain method. In this paper, we propose a special method for the numerical solution of elliptic equations with strongly varying coefficients. A theorem is proved for the rate of convergence of the iterative process developed. A computational algorithm and numerical calculations are developed to illustrate the effectiveness of the proposed method.
Źródło:
International Journal of Electronics and Telecommunications; 2014, 60, 3; 219-223
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field and experimental research on airflow velocity boundary layer in coal mine roadway
Autorzy:
Luo, Yonghao
Zhang, Yangsheng
Powiązania:
https://bibliotekanauki.pl/articles/220243.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kopalnia węgla
tunel aerodynamiczny
pomiary
coal mine roadway
airflow velocity boundary layer
mine measurements
wind tunnel simulation
supporting method
logarithm distribution
Opis:
There is an airflow velocity boundary layer near tunnel wall when the air is flowing in the underground coal mine. The thickness and distribution of the airflow velocity boundary layer could influence the discharge of harmful and toxic gases that enter the ventilating airflow through this flow interface. It may also have a major impact in coal mine gas explosion. The results of field measurements and simulation experimental data are used to research airflow velocity boundary layer in a flat walled mine roadway, which is considered in turn: as unsupported, I-steel sectioned arch or bolted and shot create supported cross section. By referenced to other literature studies that consider boundary layer characteristics and the analysis of on-site and experimental data sets we obtain the corresponding airflow velocity boundary layer characteristics for each of the supported roadway sections. The airflow velocity within the boundary layer increase is assumed to follow a logarithmic law given by the expression: u = a Ln(x) + b. It is concluded that the thickness of the airflow velocity boundary layer is observed to significantly decrease with the airflow center velocity and to increase with roadway wall roughness. The airflow velocity distribution is found to be described by the equation: u = (m1v + n1)Ln(d) + m2v + n2, for the three types coal mine tunnel taking into account the influence of center airflow velocity.
Źródło:
Archives of Mining Sciences; 2020, 65, 2; 255-270
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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