Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ parametrów zasilania na rozkład zbrojenia w kompozycie gradientowym odlewanym w polu elektromagnetycznym

100%

Golak S.

|

tom z. 124

57-65

PL

Podstawowym problemem utrudniającym proces odlewania kompozytu gradientowego jest uzyskanie działania wyporu elektromagnetycznego przemieszczającego cząstki, przy jednoczesnym uniknięciu, niweczącego efekt segregacji zbrojenia, mieszania ciekłego metalu spowodowanego niejednorodnością pola sił. Prezentowane badania dotyczyły doboru częstotliwości zasilania, natężenia prądu i rozmiarów wzbudnika w celu ograniczenia ruchu ciekłego metalu.

EN

The main problem of the process of composite casting is to obtain a electromagnetic buoyancy force moving particles and avoid stirring of liquid metal caused by force field nonuniformity that destroys the effect of reinforcement segregation. The research concerned the optimization of supply frequency, current and dimensions of a inductor in order to limit the metal movement.

2

A forced damped vibrations of the annular plate made of functionally graded material

100%

Wirowski A. , Rabenda M.

|

nr 4

EN

The work deals with the problem of dynamics of bodies made of smart materials in which a characteristic, deterministic and microstructural construction has an influence on the macroscopic properties of the entire system. In particular, the subject of the analysis is the annular plate made of a material with functionally graded properties (FGM). On the microstructural level the structure is constructed from two materials. In the circular direction the structure is periodic. In the radial direction the averaged properties of the structure are functionally variable. The study examined the issue of forced damped vibration. The starting point of discussion is the equation of motion of a thin plate based on Kirchhoff theory. Recently, the outcome of the modeling has been obtained as a partial differential equation for the unknown slowly varying function w0. This equation, as opposed to output equations of motion with discontinuous and highly oscillating coeffi cients, has smooth slowly varying coefficients. Hence, they can be solved easily by numerical methods because of its slowly varying coeffi cient. Moreover, the study shows the exemplary solutions of model equations for the asymptotic model. There is determined the form of the first symmetrical mode shapes for a sample set task parameters and selected the initial-boundary conditions.

PL

Praca dotyczy zagadnienia dynamiki ciał wykonanych z inteligentnych materiałów, w których określona, deterministyczna budowa mikrostrukturalna ma przełożenie na makroskopowe własności całego ustroju konstrukcyjnego. W szczególności przedmiotem analizy jest płyta pierścieniowa wykonana z materiału o funkcyjnej gradacji makro-własności (FGM). Struktura ta na poziomie mikrostrukturalnym jest zbudowana z dwóch materiałów: żeber o stałej szerokości oraz matrycy. W kierunku obwodowym struktura jest periodyczna. W kierunku promieniowym uśrednione własności struktury zmieniają się w sposób funkcyjnie zmienny. W pracy badane jest zagadnienie drgań wymuszonych z uwzględnieniem tłumienia. Punktem wyjścia rozważań jest równanie ruchu płyty cienkiej według teorii Kirchhoffa. Ostatecznie w wyniku procedury modelowania otrzymano układ równań cząstkowych różniczkowych na niewiadome, wolnozmienne funkcje. Układ ten posiada ciągłe współczynniki i może być rozwiązany metodami numerycznymi. W pracy pokazano także przykładowe rozwiązanie równań modelu dla zagadnienia asymptotycznego. Określono formę pierwszej, symetrycznej postaci drgań dla kilku przykładowych zestawów parametrów zadania, wybranych warunków początkowo-brzegowych oraz wymuszenia drgań.

3

Axisymmetric steady temperature field in FGM cylindrical shells with temperature-dependent heat conductivity and arbitrary linear boundary conditions

88%

Moosaie A.

|

tom Vol. 67, nr 3

233--251

EN

An approximate analytical solution to the axisymmetric heat conduction equation for a hollow cylinder made of functionally graded material with temperature-dependent heat conductivity is presented. General linear boundary conditions are considered. The Poincaré method for regular perturbation problems is employed to obtain an analytical closed-form approximate solution for the temperature field. The hierarchical asymptotic problems are solved up to the second-order approximation. A numerical example is worked out, i.e., the one-dimensional heat conduction in the radial direction with prescribed temperatures at the boundaries. The approximate temperature profiles are compared with a numerical solution of the full nonlinear problem which provides the reference “exact” solution. A good agreement between the approximate and reference solutions is established. The convergence of the asymptotic series as well as the properties of the temperature field are studied.

4

Three-dimensional analysis of laminated plates with functionally graded layers by two-dimensional numerical model

88%

Pluciński P. , Jaśkowiec J.

|

tom Vol. 68, iss. 1

21--45

EN

This work presents a three-dimensional (3D) numerical analysis of multi-layered laminated plates in which selected layers may be made of functionally graded material (FGM), in which the Young’s modulus may change along the thickness as a consequence of a continuous and graded mixture of two materials. For the analysis, the method, known as FEM23, is applied, which uses a two-dimensional (2D) mesh, yet enables obtaining full 3D results for the layered structure. In FEM23, the layered structure may be a combination of thin and thick layers made of materials with significantly different properties. This paper presents two examples comparing the results to other numerical or analytical solutions. The examples confirm the correctness and flexibility of FEM23 for laminated plates with functionally graded layers.

5

Free vibration analysis of porous functionally graded piezoelectric microplates resting on an elastic medium subjected to electric voltages

75%

Wu C.-P. , Lin E.-L.

|

tom Vol. 74, nr 6

463--511

EN

Basing on the consistent couple stress theory (CCST), we develop a unified size-dependent shear deformation theory to analyze the free vibration characteristics of simply supported, porous functionally graded (FG) piezoelectric microplates which resting on the Winkler-Pasternak foundation are subjected to electric voltages. Various CCST-based shear deformation theories can be reproduced by incorporating their corresponding shape functions, which characterize the through-thickness distributions of the shear deformations, into the unified size-dependent theory. The reproduced CCST-based plate theories include the classical plate theory (CPT), the first-order shear deformation plate theory (SDPT), Reddy’s refined SDPT, the sinusoidal SDPT, the exponential SDPT, and the hyperbolic SDPT. The unified size-dependent theory is subsequently used to determine the natural frequencies of simply supported, porous FG piezoelectric microplates and their corresponding vibration mode shapes. The effects of the material length scale parameter, the length-to-thickness ratio, the material-property gradient index, different values of the applied voltages, the porosity parameter, different porosity distribution patterns, the Winkler spring coefficient, and the shear modulus of the surrounding medium on the natural frequencies of the porous FG piezoelectric microplates are examined and appear to be significant.