Wyniki wyszukiwania - Biblioteka Nauki

1

Investigations of a noise control of a plate with four pairs of piezoelectric elements

100%

Wiciak J.

|

2006

|

tom Vol. 31, No. 4

503-512

EN

The paper explores the potentials of reducing the amplitude of plate vibrations and radiated noise through the use of piezoelectric actuators in an asymmetric configuration. Tests were run on a aluminium plate, bonded on one edge. On one of the surfaces there were four piezoelectric actuators, on the other surface there were four piezoelectric sensors. One of the actuators served as vibrations generator, while the remaining were used for vibration control. The influence of the actuators activation and shape form on the structure's response are investigated. The finite element method analysis was performed, with the application of the ANSYS computer package, and then obtained results were confirmed experimentally.

2

Scaled Soil-Structure Interaction Model for Shaking Table Testing

100%

Goktepe F. , Omid A. , Celebi E.

Acta Physica Polonica A

|

2017

|

tom 132

|

nr 3

588-590

EN

The primarily goal of this study is to reveal a scaled soil-structure interaction model for small capacity shaking table testing instead of the full-scale field experiments. The prototype of soil-structure interaction system with frame-type building, resting on a sandy soil with shear wave velocity of 536 m/s and unit weight of 12.9 kN/m³ has been selected. For experimental investigations, the realistic site and building structures are scaled with a geometric scaling factor of 1:45. The test model, consisting of six-story steel frame-type building, natural soil and laminar soil container, is designed and constructed to realistically simulate the seismic soil-structure interaction effects of building structures in shaking table tests. In order to verify the geometric scaling factor, the dynamic properties of the fixed-base system for both prototype and scaled model are determined by using finite element analysis. Furthermore, the dynamic parameters for scaled model of a single layer soil, restricted with base-rock, have been compared numerically with the proposed laminar soil container, to provide a good agreement.

3

Sensitwity analysis in a fatigue delamination problem of an elastic two-layer composite

100%

Figiel Ł. , Lauke B. , Kamiński M.

|

tom Vol. 56, iss. 1

65-87

EN

Several parameters can affect the fatigue delamination growth in laminates - these in-clude e.g. constituent material properties and/or composite shape. Knowledge about effects of these parameters can lead to a better understanding of the fatigue delamination behaviour and can also pinpoint directions for optimum composite design. These effects can be elucidated by carrying out an appropriate sensithdty analysis. A FEM-based computational approach to sensitivity analysis is proposed in this work to study composite parameter effects in a fatigue delamination problem of an elastic two-layer composite. It is used to calculate and analyse sen-sitivity gradients of the fracture parameter and fatigue cycle number with respect to composite design parameters such as layer elastic constants. It is observed that sensitivities computed from this approach are generally numerically stable. Obtained sensitivities pinpoint ąuantita-tively the most and least important composite parameters that govern a fatigue delamination process. Sensitivity results are verified by another computational approach and a very good agreement is found.

4

Facture energy of bonded joints with 2D elastic adhesive layer

100%

Budzik M. , Jumel J. , Shanahan M. M.

|

tom Vol. 10, nr 3(25)

4-16

EN

When bonded joint is subjected to mode I fracture loading, the adhesive joints analytical solutions treats the adhesive layer, usually, as not existing or 1D Hook elastic layer. In the case of 1D elastic layer, represented as Hooks spring element, is acting, only, in direction contrary to the applied load. Basing on the information yielded from sensitive laser profilometry technique, where deflections of bonded part of the joint were measured, within this contribution, 2D Finite Element Method model is introduced. The FEM allows adhesive layer to be simulated as two perpendicular-acting Hook's springs, thus in-plane shear compliance is enabled. Subsequently, appropriate analysis were carried out. Results, in terms of plate deflection, were compared with laser profilometry technique and common analytical solutions. It is concluded that linear 1D model is not sufficient for the asymmetric bonded joint configuration since the adhesive resists actively also in the in-plane shearing direction. Omitting shearing compliance effect can lead to valuable misinterpretation of the fracture energy, up to 20% in cases studied, and thus, cannot be ignored. Finally, power law based, correction factors are given promising fast and reliable data correction.

5

On modelling and analysis of piezoelectric smart structures by the finite element method

100%

Gabbert U. , Berger H. , Koppe H. , Cao X.

|

2000

|

tom Vol. 5, no 1

127-142

EN

In the paper, a general purpose finite element software for the simulation of piezoelectric material systems and controlled smart structures is presented. The equations of coupled electromechanical problems are given in a weak form, which are used for the development of 1D, 2D, 3D as well as multilayered composite shell elements. The smart structures finite element code includes static and dynamic analysis, where also controlled problems can be simulated. To demonstrate the capability of the simulation tool some test examples are reviewed.

6

A Complete Model for Iron Losses Prediction in Electric Machines Including Material Measurement, Data Fitting, FE Computation and Experimental Validation

88%

Zhao H. , Luo Y. , Ren W. , Peter B.

|

2012

|

tom R. 88, nr 5b

52-55

EN

This paper presents a complete model & process for predicting the iron losses in electric machines. The method includes material measurement, data fitting for loss coefficient determination, FE computation and experimental validation. The model is based on the loss separation of hysteresis and eddy-current losses. Also a least squares based method of curve fitting, to obtain material loss coefficients for FE analysis, is derived from the tested specific core losses of a steel lamination ring sample. The generality of the completed method is further verified b application to different steel types and electric machines. The results predicted by the model show excellent agreement with the tested data for a high speed PM DC motor and a PM BLDC motor.

PL

Zaprezentowano metodę przewidywania strat w maszynach elektrycznych uwzględniając właściwości materiałowe, współczynniki strat, obliczenia numeryczne i weryfikację eksperymentalną.

7

Probabilistic finite element analysis of a pressure vessel

88%

Gorla R. S. R. , Pratt D. M.

|

2007

|

tom Vol. 12, no 4

951-963

EN

Stress analysis of a pressure vessel was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rate due to the structural and thermodynamic random variabIes. These results can be used to quickly identify the most critical design variabIes in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in structural and heat transfer analysis and to the identification of both the most critical measurements and parameters.

8

Analysis of the structural response of Beirut port concrete silos under blast loading

88%

Ismail S. A. , Raphael W. , Durand E. , Kaddah F. , Geara F. , Ismail S. A. , Raphael W. , Durand E. , Kaddah F. , Geara F.

|

nr 3

9

Spatial modelling of sliding transformers for contactless electrical energy delivery systems

75%

Łastowiecki J. , Staszewski P.

|

2008

|

tom R. 84, nr 11

9-13

EN

This paper presents the 3D modelling of sliding transformers with rectangular and toroidal core and with a movable secondary winding. The calculations of magnetic field distribution have been made using the 3D Finite Element Method (FEM). These results are compared to those using the 2D FEM. Experimental tests on a model of transformer with a toroidal amorphous core were carried out. Conclusions on the usefulness of 2D and 3D numerical methods of analysis are drawn. A comparison of calculation and measurement results is finally made.

PL

Artykuł dotyczy zagadnień przestrzennego modelowania transformatorów ślizgowych z rdzeniem prostokątnym i toroidalnym i z ruchomym uzwojeniem wtórnym. Obliczenia rozkładu pola magnetycznego wykonano z zastosowaniem trójwymiarowej metody elementów skończonych (MES - 3D). Wyniki te porównano z analogicznymi rezultatami obliczeń uzyskanymi przy zastosowaniu MES - 2D. Dla transformatora z rdzeniem toroidalnym z materiału amorficznego wykonano badania laboratoryjne. Przedstawiono wnioski w zakresie użyteczności stosowania dwu i trójwymiarowej analizy polowej. Wyniki obliczeń porównano z wynikami badań eksperymentalnych.

10

Influence of magnetic wedge on the characteristics of 3-phase high-voltage induction motor

75%

Barański M.

|

2007

|

tom Vol. 56, nr 2

173-182

EN

Influence of the magnetic wedge material permeability on basic parameters of a squirrel cage motor was analysed. The study was based on the field-circuit model of asynchronous machine. The algorithm for solving the equations of the model was discussed. In the analysis the nonlinearity of the magnetic circuit and skewed slots of the rotor have been taken into account. A four-pole, three-phase, 5500 V, 50 Hz, 875 kW induction motor has been considered. The electromagnetic torque and phase current time curves have been calculated. Selected results of simulation tests were shown.

PL

W pracy przedstawiono wpływ przenikalności magnetycznej klina na podstawowe charakterystyki wysokonapięciowego silnika indukcyjnego klatkowego. Rozważania przeprowadzono w oparciu o polowo-obwodowy model zjawisk. Omówiono algorytm rozwiązywania równań tego modelu. Przy analizie wybranych stanów pracy silnika uwzględniono nieliniowość obwodu magnetycznego oraz skos żłobków wirnika (model wielowarstwowy). Analizie poddano 4-biegunowy, 3-fazowy silnik o następujących parametrach U(N) = 5500 V, ∫N = 50 Hz, P(N) = 875 kW. Wyznaczono przebiegi momentu elektromagnetycznego i prądów fazowych. Przedstawiono wybrane wyniki badań symulacyjnych.

11

Narzędzie wspomagające analizę numeryczną odkształceniowego zachowania się materiałów polikrystalicznych z wykorzystaniem modelu plastyczności kryształów

75%

Sitko M. , Wajda W. , Madej Ł.

|

2012

|

tom R. 57, nr 10

293-298

PL

W artykule przedstawiono model plastyczności kryształów (CP - crystal plasticity) sprzężonego z modelem cyfrowej reprezentacji materiału (DMR ang. Digital Material Representation). Dla ułatwienia przygotowania danych wejściowych do symulacji opracowano dedykowany program komputerowy wspomagający pracę z modelami plastyczności kryształów. Zastosowanie cyfrowej reprezentacji materiałów do odwzorowania mikrostruktury materiału w połączeniu z modelem CP pozwoliło na przeprowadzenie symulacji numerycznej deformacji próbki w płaskim stanie odkształcenia i analizę niejednorodności odkształcenia. Niejednorodność odkształcenia jest modelowana z uwzględnieniem zmian morfologii ziaren jak również zmian ich orientacji krystalograficznej. Kolejne etapy analizy niejednorodności odkształcenia z wykorzystaniem modeli CP i DMR są omówione w ramach niniejszej pracy.

EN

Part of the research dedicated to development of a user friendly numerical system based on the digital material representation (DMR) idea is the subject of the present paper. To facilitate preparation of a complex numerical model for modeling evolution of crystallographic orientation in subsequent grains during plastic deformation a dedicated computer program has been developed. Description of the developed program as well as its capabilities are discussed within the paper. Examples of application are presented using the numerical model of plane strain compression as a case study. As a result strain and stress inhomogeneities, changes in grain morphology as well as evolution of crystallographic orientations during deformation are easily modeled.

12

FE based structural reliability analysis using STAND environment

75%

Stocki R. , Kolanek K. , Knabel J. , Tauzowski P.

|

2009

|

tom Vol. 16, No. 1

35-58

EN

An assessment of structural reliability requires multiple evaluations of the limit state function for various realizations of random parameters of the structural system. In the majority of industrial applications the limit state functions cannot be expressed explicitly in terms of the random parameters but they are specified using selected outcomes of the FE analysis. In conseąuence, in order to be useful in practice, a structural reliability analysis program should be closely integrated with a FE module or it should be interfaced with an advanced external FE program. When the FE source code is not available, which is usually the case, the only option is to establish a communication between the reliability analysis program and an external FE software through the batch mechanism of data modification, job submission and results extraction. The main subject of this article is to present the reliability analysis capabilities of STAND software, which is being developed in the Institute of Fundamental Technological Research of Polish Academy of Sciences. A special emphasis is put on the issues related to its interfacing with external general purpose FE codes. It is shown that when shape type random variables are used, leading to modifications of the FE mesh, or when the limit state function contains numerical noise, standard algorithms for localizing the design point often fail to converge and a special method based on some response surface approximation is needed. A proposition of such a strategy that employs an adaptive response surface approximation of the limit state function is presented in this article. Development of a reliability analysis program is a challenging project and calls for such a code organization, which would facilitate a simultaneous work of many programmers and allow for easy maintenance and modifications. The so-called object-oriented programming seems to provide a convenient framework to realize these objectives. The object-oriented approach is used in STAND development. The advantages of this programming paradigm and a short description of the STAND's class hierarchy are presented in the text. The study is concluded with two numerical examples of interfacing STAND with state of the art commercial FE programs.

13

Application of numerical modelling to scaling-up of electrically induced extraction from an organic mixture using an ionic liquid

75%

Kamiński K. , Weatherley L. R. , Petera J.

|

nr 1

14

Finite element stress and strain analysis of a solid tyre

75%

Suripa U. , Chaikittiratana A.

|

2008

|

tom Vol. 31, nr 2

576-579

EN

Purpose: In this work, a finite element model of a solid tyre was constructed to simulate the loading condition. The solid tyre being modeled constitutes of three rubber layers with different properties and steel wires. Only hyperelastic property is considerd for the rubbers. The validation of FE prediction against experimental results was undertaken. An example of how arrangement of rubber layers in solid tyre can affect the distribution of strain energy density and deflection under loading was also carried out using FE analysis. Design/methodology/approach: A finite element model of a solid tyre was constructed to simulate the static compressive loading condition. The solid tyre being modeled constitutes of three types of rubber of components and steel wires Findings: The 3D FE model for static loading analysis of solid tyre constructed in this study can give reasonably good prediction of load-deflection behaviour of a real solid tyre. It can also be deduced that the distributions of analysis parameters such as strain energy density and Von Mises stress given by the FE analysis are acceptable and can be used to improve the design of solid tyres. The tyre made entirely with the rubber of the same hyperelastic property as the tread layer can give more flexible deformation and thus more comfortable ride with lesser risk to damage due to heat generation. Practical implications: Finite element analysis, as has been demonstrated, can be used to predict the performance of the solid tyre when such variations are made. The results from finite element anaysis can be used to determine the optimum thickness of each layer for green tyre (unvulcatised tyre) building. Originality/value: In the solid tyre manufacturing point of view, improving the load bearing performance by changing thickness of each solid tyre layer or make a variation in layers arrangement is the least problematic and can be done effectively without changing the mould or rubber compounds.

15

3D elasto-plastic FEM analysis of the sheet drawing of anisotropic steel sheet

75%

Trzepieciński T.

|

2010

|

tom Vol. 10, no 4

95-106

EN

The article presents the experimental and numerical results of rectangular cup drawing of DC03 coldrolled steel sheet. The aim of the experimental study was to analyse material behaviour under deformation. The received numerical results were further verified by experimental results. A 3D parametric finite element model was built using the commercial package ABAQUS. If the material and friction anisotropy are taken into account in the numerical model, this approach undoubtedly gives the most approximate numerical results to real processes.

PL

W pracy przedstawiono wyniki badań eksperymentalnych oraz symulacji numerycznych procesu kształtowania wytłoczek z blachy stalowej głębokotłocznej. Celem badań eksperymentalnych była analiza płynięcia materiału pod wpływem deformacji plastycznej. Otrzymane wyniki symulacji numerycznych zostały zweryfikowane z wynikami eksperymentalnymi. Model numeryczny 3D, bazujący na metodzie elementów skończonych, zbudowano w programie ABAQUS. Uwzględnienie w modelu numerycznym anizotropii plastycznej materiału oraz anizotropii tarcia warunkuje otrzymanie wyników bardziej zbliżonych do wyników rzeczywistego procesu kształtowania.

16

Numerical mesoscopic analysis of fracture in fine-grained concrete

75%

Skarżyński Ł. , Tejchman J.

|

nr 3

17

Computational approach for predicting the crack propagation of stainless steel plate using damage mechanics

75%

Yoo B. M. , Lee C. S. , Chun M. S. , Kim M. H. , Lee J. M.

|

2011

|

tom Vol. 11, No. 2

303-308

EN

The aim of this study is development of numerical method for the prediction for crack propagation of stainless steel plate under cryogenic temperature. Stainless steel is one of the most functional materials at relatively wide temperature ranges. It has strong non-linearities on the mechanical properties under cryogenic temperature such as discontinuous hardening phenomenon induced by the phase transformation, among others. The nonlinear hardening affects significant change of material characteristics, i.e., strength, deformation and fracture phenomenon. This induces some difficulties on the precise evaluation of structural capacity of stainless steel based structures. In the present paper, the crack propagation characteristics of the stainless steel plate under cryogenic temperature have been simulated using a new numerical technique based on a newly proposed damage-coupled constitutive model and orient-purpose user subroutine applicable to commercial FEA code ABAQUS. The numerical results are compared with the experimental results of tensile test and crack propagation tests under cryogenic temperature.

PL

Celem pracy jest opracowanie numerycznej metody przewidywania propagacji pęknięć w blachach grubych ze stali nierdzewnej w temperaturach kriogenicznych. Stal nierdzewna jest jednym z najbardziej funkcjonalnych materiałów w szerokim zakresie temperatur. Charakteryzuje się mocną nieliniowością własności mechanicznych w temperaturach kriogenicznych, między innymi nieciągłym umocnieniem wywołanym przemianą fazową. Nieliniowe umocnienie wpływa znacząco na takie charakterystyki materiału jak wytrzymałość, odksztacalność i pękanie. Zjawisko to powoduje trudności w oszacowaniu możliwości konstrukcyjnych zastosowań stali nierdzewnych. W artykule przeprowadzono symulacje charakterystyk propagacji pęknięć w blachach grubych ze stali nierdzewnych w temperaturach kriogenicznych. Zastosowano w tym celu nową numeryczną technikę opartą o model konstytutywne sprzężony z pękaniem, wprowadzany jako procedura użytkownika do programu ABAQUS. Wyniki symulacji numerycznych porównano z doświadczalnymi próbami rozciągania w temperaturach kriogenicznych.

18

Modeling and simulation of elasto-viscoplastic anisotropic behavior of tantalum including the ductile damage effect

75%

Paris T. , Saanouni K. , Francois M. , Delaplanche D.

|

2009

|

tom Vol. 9, No. 1

25-29

EN

At room temperature, the tantalum is shown to exhibit a high and typical strain rate sensitivity. Various experimental tests including uniaxial tensile test in the three plane direction, relaxation and cyclic shear tests have been conducted at room temperature in order to study the mechanical behavior of tantalum. Based on this experimental data, an elasto-viscoplastic model is developped including the initial viscoplastic anisotropy as well as the isotropic ductile damage effects using an enhanced viscosity effect. Using the framework of the thermodynamics with state variables, an appropriate state and dissipation potentials are proposed to account for, the initial viscoplastic flow anisotropy, the mixed non linear isotropic and kinematic hardenings and the isotropic ductile damage effect. Specific developments are made to introduce different isotropic type hardenings thanks to a coupling between cumulative plastic strain and viscous or kinematic hardening effects. The proposed model, implemented into ABAQUS explicit via the user subroutine vumat, is used to simulate different experimental tests in order to determine the accurate values of the overall material parameters. The special treatment of the plane stress case is addressed and shown to describe the anisotropic behavior. Finally, some simple 2D and 3D simulations of deep drawing tests are carried out to validate the accuracy of the proposed model.

PL

W temperaturze pokojowej tantal wykazuje typową wysoką wrażliwość na prędkość odkształcenia. Szereg testów, w tym jednoosiowy test rozciągania, relaksacji i cykliczny test ścinania, zostało przeprowadzonych w temperaturze pokojowej w celu poznania mechanicznych własności tantalu. Bazując na otrzymanych danych eksperymentalnych opracowano sprężyste lepko plastyczny model uwzględniający początkową lepko plastyczną anizotropię jak również izotropowy efekt plastycznego pękania. Wykorzystując termodynamiczne podejście ze zmiennymi stanu zostały zaproponowane zmienne stanu i potencjały dyssypacyjne aby uwzględnić anizotropie w początkowym lepko plastyczny płynięciu, oraz aby połączyć nieliniowe izotropowe i kinematyczne modele umocnienia oraz efekty plastycznego pękania. Szczególny nacisk położono na opracowanie złożonych modeli umocnienia materiału. Opracowany model zaimplementowano w programie ABAQUS/EXPLICIT przez procedurę użytkownika Vumant. Model ten został wykorzystany do symulacji różnych testów w celu identyfikacji dokładnych wartości parametrów materiałowych. W pracy przedstawiono również wyniki prostych symulacji w 2D i 3D testów głębokiego tłoczenia przeprowadzone w celu weryfikacji poprawności proponowanego modelu.

19

Finite element analysis of elliptic cup deep drawing of magnesium alloy sheet

75%

Yang T. S.

|

2008

|

tom Vol. 27, nr 2

139-142

EN

Purpose: In magnesium alloy sheet products have been attracting more and more attention in recent years because of their application potentials as coverings of portable electrical devices and automotive panels. Thus this paper focus on the deep drawing process of magnesium alloy sheet. Design/methodology/approach: The FEM soft ware DEFORM-3D is used to investigate the mateial flow character during the elliptic cup deep drawing of magnesium alloy sheet at elevated temperatures. Findings: Investigate the effective stress and forming load under various process parameter conditions, including the profile radius of die, the clearance between die cavity and punch, the blank holding force and working temperature during the elliptic cup deep drawing of magnesium AZ31 alloy sheet. Research limitations/implications: The initial blank's shape design and forming limit analysis of the elliptic cup deep drawing of magnesium AZ31 alloy sheet will be continued for future research. Originality/value: The original value of this paper is the finite element method is used to investigate the material flow character, forming load, stress and strain distribution during the the elliptic cup deep drawing of magnesium alloy sheet at elevated temperatures.

20

Design, prototype and experimental evaluation of a wheelchair treadmill

75%

Kurt M. , Geyik H. , Mutlu B. , Tatar Y. , Nart E.

|

2008

|

tom Vol. 2, no. 3

71-75

EN

Generally, wheelchair users cannot move easily within buildings since living areas in architectural structures are not suitable for them to maintain or to improve their physical capabilities. Because living area restrictions affect the physical performance of the users outside during the day, the reduced mobility causes several health problems. These problems become more intense by the time. Especially heart and lung related illnesses are common among the wheelchair users since the immobility decreases respiration capacity. The aim of this research is to design and prototype a wheelchair treadmill to help wheelchair users improve their upper extremity system. In this study, CAD was employed for the design of wheelchair treadmill. Then finite element analysis (FEA) was carried out for the parts of the wheelchair treadmill and the prototype was manufactured based on the results. The prototype was tested under the conditions the product was originally intended to function. In the experiments, the speeds of wheelchair and wheelchair treadmill were measured. The distances taken by users were also recorded, and the results were evaluated with respect to road surface conditions.