Wyniki wyszukiwania - BazTech

1

Multiparameter fault identification in elastic elements of constructions based on artificial neural networks

Krasnoschekov A.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2011

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z. 99

33-35

EN

Identification of defects is a critical aspect in the operational safety and func- tionality of elastic structures. It’s well known that changes in a structure of the material, entail a change in its dynamic properties. One of the most commonly used methods for determination of these properties is modal analysis, with witch we obtain spectrum of natural frequencies and forms of investigated object. This data can be used to identify presence of the defect and it's quantative parameters (like location or size). In recent years many studies in this direction were held and artificial neural networks (ANN) are increasingly used for reconstruction of inhomogeneities [1,2]. In this article we propose a method that includes the complete cycle of designing ANN for identification of defects in a given 3-D object: starting from a model and ending with location of sensors on the object's surface and trained ANN. The problems of constructing simulation model of the object, optimal placement of sensors and subsequent identification of the defect were solved. We've also investigated possibilities of application of different architectures and training algorithms of ANN, and analyzed the influence of errors on the accuracy of determination of the defect's parameters. Simulation model in the purposes of the study in ANSYSŽ we've built 3-dimensional FE mod- el of the beam of rectangular cross section with a through crack which is coming out on top of the face (Fig. 1). The left end is rigidly clamped, right - free.

2

Równania więzów pomiędzy układem wieloczłonowym i modelem złożonym z elementów skończonych

Lipiński K.

Modelowanie Inżynierskie

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2010

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T. 8, nr 39

127-134

PL

W pracy zaprezentowano równania punktowego kontaktu pomiędzy układem wieloczłonowym i strukturą odkształcalną. Układ wieloczłonowy zbudowano z nieodkształcalnych członów połączonych parami kinematycznymi. Część odkształcalną zbudowano z elementów skończonych. Zarysowano sposób wyznaczania równań modelu wieloczłonowego i modelu odkształcalnego. Wyznaczono równania więzów. Układ algebraiczno różniczkowy przekształcono do postaci różniczkowej. Wykorzystano do tego dedykowaną wersję metody podziału zmiennych. Wyeliminowano współrzędne zależne i mnożniki Lagrange'a. Zagadnienie zilustrowano przykładem numerycznym.

EN

In the paper, constraint equations are presented for a punctual contact between a multibody system and an elastic structure. The multibody system is composed of rigid bodies, joined by kinematic pairs. The elastic structure is built of deformable finite elements. Dynamic equations of the both (the multibody and the finite elements) models are presented. The main zoom is set on the constraint equations. Then the differentially-algebraic system of equations is transformed into a differential set of equations, by used of a dedicated version of the coordinate partitioning technique. Dependent coordinates, as well as the Lagrange' multipliers are eliminated. The method is illustrated with a numerical example.

3

Synchronisation and periodisation of duffing oscillators coupled by elastic beam: finite element method approach

Chudzik A.

Journal of Theoretical and Applied Mechanics

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2010

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Vol. 48 nr 2

517-524

EN

Results of numerical analysis of a structure witch consists of two identical chaotic oscillators suspended on an elastic element are presented. The numerical calculations have been carried out with the use of the professional ANSYS software (User's Gude ANSYS 10). The findings show that for given conditions of the excitation, the initially uncollerated chaotic oscillations of the structure become periodic and synchronous.

PL

W artykule przedstawiono wyniki analizy numerycznej struktury składającej się z dwóch identycznych chaotycznych oscylatorów zawieszonych na sprężystej belce. Obliczenia numeryczne przeprowadzono stosując profesjonalny pakiet programu ANSYS. Wykazano, że dla danych warunków wzbudzenia, początkowo nie są skorelowane, chaotyczne oscylacje struktury stają się okresowe i synchroniczne. W warunkach, kiedy częstości wzbudzenia różnią się, zjawiska powyższe nie występują.

4

Dynamics of System Coupled by Elastic Structures

Chudzik A.

Machine Dynamics Problems

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2009

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Vol. 33, No. 1

16-22

EN

The subject under consideration is the dynamics of two non-linear chaotic oscillators attached to an elastic beam. Duffing oscillators are stimulated by a periodic signal at w frequency. The conclusion is that for given conditions initially uncorrelated chaotic oscillators becomes periodic and synchronous as a result of interaction with the elastic beam. Another interesting observation concerns the responses of the elastic beam and the oscillators to the excitations without the synchronization of their oscillations. The numerical calculations has been achieved with the use professional ANSYS program.

5

Dynamics of an Array of Duffing Oscillators Suspended on Elastic Etructures

Czołczyński K., Stefański A., Perlikowski P., Kapitaniak T.

Machine Dynamics Problems

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2007

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Vol. 31, No. 2

57-65

EN

We consider the dynamics of externally excited chaotic oscillators suspended on the elastic structure. We show that for the given conditions of oscillations of the structure, initially uncorrelated chaotic oscillators become periodic and synchronous. In the periodic regime we observed synchronized clusters and multistability as different attractors coexist.

6

Evolutionary algorithms in selected optimization and identification problems of mechanical systems

Burczyński T., Beluch W., Kuś W., Nowakowski M., Orantek P.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2002

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z. 139

87--121

EN

This chapter deals with applications of evolutionary algorithms to the topology optimization of elastic structures, shape optimization of elasto-plastic structures, the identification of voids and cracks in structures under dynamical loading and the identification and optimization of boundary conditions in cracked structures.

7

On macrodynamics of elastic chess-board structures

Wierzbicki E., Woźniak C.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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1998

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z. 6

359-362

EN

A simplified model of the dynamic behaviour for linear-elastic chess board structures is proposed. The propagation of waves across these structures is investigated in the framework of the model. The existence of Jhe well defined on the macro-level dilatational and distorsional waves is shown.

PL

Zaproponowano uproszczony model opisujący dynamikę liniowo-sprężystych układów szachownicowych. Model wykorzystano do badania rozchodzenia się fal w takich układach. Wykazano istnienie odpowiednio zdefiniowanych na poziomie "makro" fal dylatacyjnych i dystorsyjnych.