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1

Effective Thermal Characteristics Synthesis Microlevel Models in the Problems of Composite Materials Optimal Design

Jaworski N.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2015

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Vol. 4, No 2

3--12

EN

The composite materials optimal design problem which taking into account the thermal characteristics is the part of an actual structural design task. A wide range of variety of such material structures and the complexity of modeling some physical phenomena (such as the phenomenon of those structures effective characteristics percolation threshold appearing) requires a high level of detail in physico-mathematical models. Here, in this paper, were analyzed the role and place of physico-mathematical microlevel models in problems of composite materials optimal design. The methods of such materials representative volume elements construction within the model calculations, which are the key step in the modeling of complex structures variety, also were analyzed. Basing on the usage of finite element method for modeling of stationary heat conduction and elasticity linear problems was proposed the combined formalization of coupled thermoelasticity problems simulation method in complex structured composite materials, which is especially useful when used in engineering applications which provide a high level of abstraction. Basing on the analogy method and theory of similarity were developed the complex structured composite materials microlevel models, which allow one to synthesize and then re-use in the problems of composite materials optimal design, such effective thermal characteristics as thermal conduction coefficient, Young's modulus, Poisson's ratio and temperature coefficient of linear expansion. This gives the ability to avoid of classical complex mathematical homogenization processes or real experiments. The method and models were successfully implemented by using of highperformance parallel and distributed computing technologies in heterogeneous computing environments, as evidenced by the simulation results.

2

Optimization in multiscale thermoelastic problems

Długosz A.

Computer Methods in Materials Science

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2014

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Vol. 14, No. 1

86--93

EN

The paper is devoted to the optimization of two-scale thermoelastic problems. The problem is solved by means of evolutionary computation and a direct analysis based on a numerical homogenization. Direct thermoelastic analysis with representative volume element (RVE) and finite element method (FEM) is taken into account. Design variables in optimization tasks describe micro-structure, whereas functionals are formulated on the basis of the quantities derived from a macro scale. Numerical examples of optimization are included.

PL

W artykule przedstawiono połączenie modelowania wieloskalowego dla układów termosprężystych oraz wielokryterialnego algorytmu ewolucyjnego. W pracy przedstawiono przykłady optymalizacji parametrów mikrostruktury porowatej, z której wykonany jest układ poddany obciążeniom termomechanicznym. Zadania polegały na optymalnym doborze kształtu pustki w mikrostrukturze modelowanej za pomocą zamkniętej krzywej NURBS. Zdefiniowano kilka funkcjonałów, zależnych od przemieszczeń i strumienia ciepła w skali makro oraz od porowatości mikrostruktury. Optymalizację wielokryterialną przeprowadzono dla wybranych par funkcjonałów z użyciem opracowanego algorytmu MOOPTIM.

3

Identiﬁcation in multiscale thermoelastic problems

Długosz A., Burczyński T.

Computer Assisted Methods in Engineering and Science

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2013

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Vol. 20, no. 4

325--336

EN

The paper deals with the identiﬁcation in multiscale analysis of structures under thermal and mechanical loads. A two-scale model of porous materials is examined. Direct thermoelastic analyses with representative volume element (RVE) and ﬁnite element method (FEM) are taken into account. Identiﬁcation of material constants of the microstructure and identiﬁcation of the shape of the voids in the microstructure are considered. Identiﬁcation functional is formulated on the basis of information obtained from measurements in mechanical and thermal ﬁelds. Evolutionary algorithm is used for the identiﬁcation as the optimization technique. Numerical examples of identiﬁcation for porous aluminum models are enclosed.

4

Computer simulation of free boundary in process of levitation induction melting

Dolezel I., Mach M.

Przegląd Elektrotechniczny

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2006

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R. 82, nr 12

69-71

EN

The paper deals with computer modeling of selected processes accompanying levitation melting that is controlled by electromagnetic field. Particular attention is paid to the free boundary of melt whose shape follows from the balance of all forces acting on its surface. The paper presents the mathematical and computer models of the problem and algorithm of its solution. The theoretical analysis is illustrated on a typical example whose results are discussed.

PL

W artykule przedstawiono modelowanie komputerowe wybranych procesów towarzyszących topieniu lewitacyjnemu, sterowanej polem elektromagnetycznym. Szczególną uwagę zwrócono na swobodne brzegi płynnego stopu, które kształtuje równowaga sił działających na jego powierzchni. Zademonstrowano model matematyczny i model komputerowy oraz algorytm jego rozwiązania. Analiza teoretyczna została zilustrowana typowym przykładem obliczeniowym.

5

Analysis of weakly-coupled electromagnetic and temperature fields in transverse flux induction heating system for non-ferromagnetic strips

Barglik J.

Archives of Electrical Engineering

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2005

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Vol. 54, nr 1

93-108

EN

Induction heating of metal work-pieces in transverse flux magnetic field (THIFS) belongs to modern industrial technologies. This kind of heating is fast, environmentally friendly and especially effective in case of thin, flat strips of the thickness comparable with the depth delta of electromagnetic field penetration. The arrangement makes it possible to easily achieve suitable parameters for induction heating of thin non- ferromagnetic strips in the process of their annealing at relatively low frequencies of the field current. The paper presents a mathematical model of resultant electromagnetic and temperature fields in the system and its most important local and integral characteristics. Computations (realised in weakly-coupled formulation) are compared with experiments obtained on a laboratory stand. The agreement between calculated results and measured data is very good. An illustrative example demonstrates that uniform temperature distribution along the width of the charge may be achieved by selection of suitable frequency of the field current.

PL

Nagrzewanie indukcyjne wsadów metalowych w poprzecznym polu magnetycznym zalicza się do nowoczesnych technologii przemysłowych. Ten szybki, proekologiczny rodzaj nagrzewania jest szczególnie efektywny w przypadku cienkich wsadów płaskich o grubości taśmy porównywalnej z głębokością wnikania pola elektromagnetycznego delta. Układ umożliwia łatwe uzyskanie wymaganych parametrów nagrzewania indukcyjnego wsadów nieferromagnetycznych w procesie ich wyżarzania przy stosunkowo małej częstotliwości prądu wzbudnika. W pracy omówiono trójwymiarowy model matematyczny pola elektromagnetycznego i temperaturowego dla tego układu oraz scharakteryzowano jego najważniejsze parametry lokalne i integralne. Obliczenia komputerowe (zrealizowane jako słabo-sprzężone) zostały uzupełnione wynikami badań na stanowisku laboratoryjnym. Uzyskano małe rozbieżności między wynikami obliczeń i pomiarów. Przykład obliczeniowy wskazuje, że aby uzyskać równomierny rozkład temperatury w szerokości taśmy należy wybrać odpowiednią wartość częstotliwości prądu wzbudnika.

6

Computational challenges in MEMS

Furuberg L.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 1

173-185

EN

Small sensors and actuators made from materials like silicon, quartz or plastic are already parts of our everyday life. In cars there are often silicon sensors measuring acceleration, tyre pressure and car roll-over. There may be microfabricated mechanical components inside your light projector or in your ink-jet printer. In the future, microsystems are believed to be widespread, being used for environment monitoring, safety systems, medical care and biochemical analyses. The small mechanical elements are easily integrated in electrical circuits that control their behaviour, process their output signals or interconnect several active and passive elements in a control system. Behaviour of the mechanical elements is often governed by interacting elastic forces, electromagnetic forces and forces due to surrounding fluids. Computation of the behaviour is therefore complicated. Engineers working with macroscopic constructions like oil-platforms, where mechanical and fluid forces interact, face similar challenges. Experiences and research results from the macroscopic world are therefore of great importance for the design of microsystems. Microsystem elements usually involve micrometer sized features. The small scale introduces effects that are negligible on larger scales, such as strong surface forces. In addition, the continuum hypothesis may break down in some problems, excluding the use of partial differential equations describing the behaviour. There are also fundamental physical effects occurring on small scales that are not yet understood. An important task in microsystems design is to develop reduced-order macromodels that capture the essential behaviour of a mechanical microelement. The complicated electrical circuits controlling the mechanical elements need to be optimised, and this will be too time-consuming without simplified descriptions. We present examples of microsystems, outline current computational technology and some remaining challenges in these fields.