Wyniki wyszukiwania - BazTech

1

Free vibration analysis of sandwich beam with porous FGM core in thermal environment using mesh-free approach

Hung Tran Quang, Tu Tran Minh, Duc Do Minh

Archive of Mechanical Engineering

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2022

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LXIX, nr 3

471--496

EN

Thermally induced free vibration of sandwich beams with porous functionally graded material core embedded between two isotropic face sheets is investigated in this paper. The core, in which the porosity phase is evenly or unevenly distributed,has mechanical properties varying continuously along with the thickness according to the power-law distribution. Effects of shear deformation on the vibration behavior are taken into account based on both third-order and quasi-3D beam theories. Three typical temperature distributions, which are uniform, linear, and nonlinear temperature rises, are supposed. A mesh-free approach based on point interpolation technique and polynomial basis is utilized to solve the governing equations of motion. Examples for specific cases are given, and their results are compared with predictions available in the literature to validate the approach. Comprehensive studies are carried out to examine the effects of the beam theories, porosity distributions, porosity volume fraction, temperature rises, temperature change, span-to-height ratio, different boundary conditions, layer thickness ratio, volume fraction index on the vibration characteristics of the beam.

2

Text-mining-based approach for conductingliterature review of selected meshfree methods

Sindhusuta S., Chi Sheng-Wei, Derrible Sybil

Computer Assisted Methods in Engineering and Science

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2021

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Vol. 28, no. 4

265--290

EN

The goal of this study is to review the literature in the field ofmeshfree methodsusing textmining. For this study, the abstracts of around 17330 relevant articles published from 1990to 2020 were collected from Scopus. Text mining techniques such as the latent Dirichletallocation (LDA), along with the calculation of term frequencies and co-occurrence coefficients were used to analyze the text. The study identified a few key topics in the field ofmeshfree methods and helped to see the evolution of the field over the past three decades.Furthermore, the trend in the number of publications and frequency map highlightedresearch trends and lack of focus in certain areas. The co-author network visualizationprovided interesting insights about collaboration between different researchers around theworld. Overall, this study facilitates a systematic literature review in the field of meshfreemethods and provides a broader perspective of the field to the research community.

3

A meshless method for subsonic stall flutter analysis of turbomachinery 3D blade cascade

Prasad Chandra Shekhar, Šnábl Pavel, Pešek Luděk

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e139000

EN

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.

4

Zastosowanie radialnych funkcji bazowych do analizy pola akustycznego wnętrz pojazdów

Majkut L.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 12

1183--1187

PL

W artykule opisano możliwości zastosowania jednej z tzw. metod bezsiatkowych do analizy pola akustycznego wnętrza pojazdu. Do analizy wybrano metodę kolokacyjną z bazą globalnych funkcji radialnych. W kolejnych punktach pracy opisano wykorzystywaną metodę analizy i jej zastosowanie do wyznaczenia częstości drgań własnych i charakterystyk amplitudowo-częstotliwościowych wnętrza przykładowego pojazdu. Charakterystyki wyznaczono w dwóch układach źródła: jedno źródło zlokalizowane na środku przedniej części pojazdu (układ siso) i dwa źródła umieszczone po bokach pojazdu (układ miso). Wartości częstości własnych porównano z analizą Metodą Elementów Skończonych.

EN

The work concerns the in acoustics of an vehicle interior with the Radial Based Functions. The collocation method was used for determination eigenvalues and frequency response functions of the car interior. All eigenvalues were compared with Finite Element Analysis results. All results indicate that using of multiquadric (MQ) RBF provide a results with very high accuracy in comparison to numerical results in acoustic analysis of 3D close domain.

5

Method of regularized sources for two-dimensional Stokes flow problems based on rational or exponential blobs

Wen S., Wang K., Zahoor R., Li M., Šarler B.

Computer Assisted Methods in Engineering and Science

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2015

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Vol. 22, no. 3

289--300

EN

The solution of Stokes flow problems with Dirichlet and Neumann boundary conditions is performed by a non-singular method of fundamental solutions (MFS) which does not require artificial boundary, i.e., source points of fundamental solution coincide with the collocation points on the boundary. The fundamental solution of the Stokes pressure and velocity is obtained from the analytical solution due to the action of the Dirac delta- type force. Instead of Dirac delta force, a non-singular function called blob, with a free parameter epsilon is employed, which is limited to Dirac delta function when epsilon is limited to zero. The analytical expressions for related Stokes flow pressure and velocity around such regularized sources have been derived for rational and exponential blobs in an ordered way. The solution of the problem is sought as a linear combination of the fields due to the regularized sources that coincide with the boundary and with their intensities chosen in such a way that the solution complies with the boundary conditions. A numerical example for two-dimensional (2D) driven cavity and a flow between parallel plates are chosen to assess the properties of the method. The results of the posed method of regularized sources (MRS have been compared with the results obtained by the fine-grid second-order classical finite difference method (FDM) and analytical solution. The results converge with finer discretisation; however, they depend on the value of epsilon. The method gives reasonably accurate results for the range of epsilon between 0.1 and 0.5 of the typical nodal distance on the boundary. Exponential blobs give slightly better results than the rational blobs; however, they require slightly more computing time. A robust and efficient strategy to find the optimal value of epsilon is needed in the perspective.

6

Numeryczne modelowanie zjawiska wybuchu

Ogierman W.

Modelowanie Inżynierskie

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2014

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T. 20, nr 51

62--69

PL

W artykule przedstawiono metodykę numerycznego modelowania zjawiska wybuchu przy użyciu metody elementów skończonych (MES) oraz bezsiatkowej metody SPH (Smoothed Particle Hydrodynamic). Zaprezentowano i porównano wyniki symulacji otrzymane wymienionymi metodami. Wartości ciśnienia fali uderzeniowej wyznaczone numerycznie zostały porównane z istniejącymi w literaturze zależnościami empirycznymi. Możliwości metod numerycznych w analizie zjawiska wybuchu przedstawiono na przykładzie analizy oddziaływania fali uderzeniowej na przykładową konstrukcję.

EN

This article presents methodology of numerical modeling of explosion phenomenon by using the finite element method (FEM) and meshless SPH (Smoothed Particle Hydrodynamic) method. Obtained simulations results are presented and compared. Computed numerically shock wave pressure values were compared with existing empirical solutions. Testing the influence of blast wave on the exemplary structure is presented as an example of capabilities of numerical methods in modeling of the explosion phenomenon.

7

A meshless method using global radial basis functions for creating 3-D wind fields from sparse meteorological data

Pepper D.W., Rasmussen C., Fyda D.

Computer Assisted Methods in Engineering and Science

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2014

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Vol. 21, no. 3-4

233-243

EN

An efficient, global meshless method has been developed for creating 3-D wind fields utilizing sparse meteorological tower data. Meshless methods do not require the need for a mesh in order to connect node points. In this study, node points are placed within the computational domain based on topological features. Wind speeds and directions are obtained from a set of instrumented meteorological towers. Inverse weighting is used to initially establish wind vectors at all nodal points. The Kansa technique, employing global basis functions, is then used to create a mass-consistent, 3-D wind field. The meshless method yields close approximations to results obtained with a high-order finite element technique. The method was implemented using MATLAB.

8

Properties of a Meshless Simulation Method of Diffusion from a Finite Source

Dawidowicz T.

Biuletyn Instytutu Systemów Informatycznych

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2011

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nr 8

25-33

EN

The paper presents an analysis of the properties of a numerical algorithm of a diffusion simulation from a finite source based on a meshless numerical method. The simulation time dependencies and simulation errors have been presented. The range of parameters were indicated for which the method achieves physical results.

PL

W pracy przedstawiono analizę właściwości algorytmu numerycznego symulacji dyfuzji ze źródła skończonego opartego o bezsiatkową metodę numeryczną. Wykazano zależności czasowe symulacji oraz przedstawiono błędy symulacji. Wskazano zakres parametrów, dla których metoda uzyskuje wyniki fizyczne.

9

Stacjonarne przewodzenie ciepła przez wielowarstwową ściankę o zależnym od temperatury współczynniku przewodzenia ciepła

Mierzwiczak M.

Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją

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2008

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Nr 9

67-79

PL

W artykule przedstawiono numeryczne rozwiązanie stacjonarnego zagadnienia przewodzenia ciepła przez wielowarstwową płaską i cylindryczną ściankę, której współczynnik przewodzenia zależy od temperatury. Do rozwiązania problemu zastosowano bezsiatkową metodę Kansy. Nieznane pole temperatury przyjmuje się w warstwach w postaci liniowej kombinacji radialnych funkcji bazowych (RBF). Kolokacyjne spełnienie równania rządzącego i warunków brzegowych prowadzi do nieliniowego układu równań rozwiązywanego metodą Newtona.

EN

This paper deals with numerical solution of heat transfer problem in multilayered plate and cylinder with temperature-dependent thermal conductivity. The Kansa meshless method was used for the solution of this problem. In this approach, the unknown's temperatures in layers are approximated by the radial basis functions, while the governing equation and the boundary conditions are imposed directly at the collocation points. The multiquadrics are used as the radial basis functions. Non-linear system of algebraic equations for coefficients at radial basis functions is solved by Newton method.

10

Metody bezsiatkowe : czy jest na nich miejsce w geoinżynierii? Rozwiązanie zagadnienia Flamanta metodą MLPG

Sikora Z., Ossowski R.

Geoinżynieria : drogi, mosty, tunele

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2007

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nr 3

42-46

PL

W artykule przedstawiono przykład zastosowania metody MLPG do rozwiązania klasycznego zagadnienia Flamanta. W metodzie MLPG do interpolacji wykorzystano uogólnioną funkcję Hardy'ego. Jako funkcję wagową zastosowano funkcję Heaviside'a. Zbadano wpływ parametrów funkcji interpolacyjnej oraz parametrów definiujących obszary całkowania na dokładność rozwiązania oraz przedstawiono wpływ zagęszczenia obszaru dyskretyzacji na dokładność rozwiązania. Przytoczone wyniki pozwalają na pozytywną weryfikację tej metody obliczeniowej w zastosowaniach wybranych obliczeń praktycznych.

EN

A short state-of-the-art "Meshless Local Petrov Galerkin Method" (MLPG) is presented. The MLPG utilized interpolation functions with the radial base and Heaviside function as the weight function, can be one of the promising computational tools in geomechanical modelling problems. This method allows to overcome some well-known drawbacks of the finite element method, e.g. problems of volumetric locking (simulations with large deformations), problems with deformation of elements, etc. This method makes possible for instance easy addition of discretization nodes during calculations, and so on. As the practical example of the use of the MLPG method a solution of the generalized Flamant problem is presented. Appraisable of the accuracy of calculations one used the analytic solution. In the first instance one chose optimum-parameters of the multiquadric Radial Basis Functions on which is based the interpolation procedure. Then one examined the computational exactitude depending on parameters defining the range of the local integration domain and the local interpolation one. The influence of the condensation of the discretization nodes and conclusions from calculations are introduced.