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1

Parallel computing in automation of decoupled fluid-thermostructural simulation approach

Glänzel Janine, Naumann Andreas, Kumar Tharun Suresh

Journal of Machine Engineering

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2020

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Vol. 20, No. 2

39--52

EN

Decoupling approach presents a novel solution/alternative to the highly time-consuming fluid-thermal-structural simulation procedures when thermal effects and resultant displacements on machine tools are analyzed. Using high dimensional Characteristic Diagrams (CDs) along with a Clustering Algorithm that immensely reduces the data needed for training, a limited number of CFD simulations can suffice in effectively decoupling fluid and thermal-structural simulations. This approach becomes highly significant when complex geometries or dynamic components are considered. However, there is still scope for improvement in the reduction of time needed to train CDs. Parallel computation can be effectively utilized in decoupling approach in simultaneous execution of (i) CFD simulations and data export, and (ii) Clustering technique involving Genetic Algorithm and Radial Basis Function interpolation, which clusters and optimizes the training data for CDs. Parallelization reduces the entire computation duration from several days to a few hours and thereby, improving the efficiency and ease-of-use of decoupling simulation approach.

2

Parameterization of environmental influences by automated characteristic diagrams for the decoupled fluid and structural-mechanical simulations

Glänzel Janine, Kumar Tharun Suresh, Naumann Christian, Putz Matthias

Journal of Machine Engineering

|

2019

|

Vol. 19, No. 1

98--113

EN

Thermo-elastic effects contribute the most to positioning errors in machine tools especially in operations where high precision machining is involved. When a machine tool is subjected to changes in environmental influences such as ambient air temperature, velocity or direction, then flow (CFD) simulations are necessary to effectively quantify the thermal behaviour between the machine tool surface and the surrounding air (fluid). Heat transfer coefficient (HTC) values effectively represent this solid-fluid heat transfer and it serves as the boundary data for thermo-elastic simulations. Thereby, deformation results can be obtained. This two-step simulation procedure involving fluid and thermo-structural simulations is highly complex and time-consuming. A suitable alternative for the above process can be obtained by introducing a clustering algorithm (CA) and characteristic diagrams (CDs) in the workflow. CDs are continuous maps of a set of input variables onto a single output variable, which are trained using data from a limited number of CFD simulations which is optimized using the clustering technique involving genetic algorithm (GA) and radial basis function (RBF) interpolation. The parameterized environmental influences are mapped directly onto corresponding HTC values in each CD. Thus, CDs serve as look-up tables which provide boundary data (HTC values along with nodal information) under several load cases (combinations of environmental influences) for thermo-elastic simulations. Ultimately, a decoupled fluid-structural simulation system is obtained where boundary (convection) data for thermo-mechanical simulations can be directly obtained from CDs and would no longer require fluid simulations to be carried out again. Thus, a novel approach for the correction of thermo-elastic deformations on a machine tool is obtained.

3

A new multigrid based method for characteristic diagram based correction of thermo-elastic deformations in machine tools

Naumann Christian, Putz Matthias

Journal of Machine Engineering

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2019

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Vol. 19, No. 4

42--57

EN

It is a well-known problem of milling machines, that waste heat from motors, friction effects on guides, environmental variations and the milling process itself greatly affect positioning accuracy and thus production quality. An economic and energy-efficient method of correcting this thermo-elastic positioning error is to gather sensor data (temperatures, axis positions, etc.) from the machine tool and the process and to use that information to predict and correct the resulting tool center point displacement using high dimensional characteristic diagrams. The computation of these characteristic diagrams leads to very large sparse linear systems of equations which require a vast memory and computation time to solve. This is particularly problematic for complex machines and varying production conditions which require characteristic diagrams with many input variables. To solve this issue, a new multigrid based method for the computation of characteristic diagrams will be presented, tested and compared to the previously used smoothed grid regression method.

4

Local temperature rise during the electron beam characterization Calculation model for the AlxGa1-xN at low dimensions

Leghrib L, Nouiri A.

Materials Science Poland

|

2018

|

Vol. 36, No. 1

51--55

EN

During the characterization by electron beam techniques including scanning electron microscope (SEM) and cathodoluminescence at low dimensions, some undesirable phenomena (unwanted effects) can be created, like the thermal effects (or electron beam damage), and these effects can damage the sample. This limits the information one can get from a sample or reduces image spatial resolution. In order to understand these effects, significant efforts have been made but these studies focused on the thermal properties, without a detailed study of the causes of nanoscale heating in the bulk of samples during the SEM-characterization. Additionally, it is very difficult to measure experimentally the heating because there are many variables that can affect the results, such as the current beam, accelerating energy, thermal conductivity and size of samples. Taking into account all the factors and in order to determine the local temperature rise during the electron beam characterization of AlGaN at low dimensions, we have used a hybrid model based on combined molecular dynamics and Monte Carlo calculation of inelastic interaction of electrons with matter to calculate the temperature elevation during the SEM-characterization which can be taken into account during the characterization of AlGaN at low dimension by electron beam techniques.

5

On the selection and assessment of input variables for the characteristic diagram based correction of thermo-elastic deformations in machine tools

Ihlenfeldt S., Naumann C., Putz M.

Journal of Machine Engineering

|

2018

|

Vol. 18, No. 4

25--38

EN

It is a well-known problem of milling machines, that waste heat from motors, friction effects on guides and most importantly the milling process itself greatly affect positioning accuracy and thus production quality. An economic and energy-efficient method of correcting this thermo-elastic positioning error is to gather sensor data from the machine tool and the process and to use that information to predict and correct the resulting tool center point displacement using high dimensional characteristic diagrams. On the one hand, the selection of which and how many input variables to use in the characteristic diagrams is critical to their performance. On the other hand, however, there are often a great number of possible variable combinations available and testing them all is practically impossible. This paper will discuss the suitability of many different input variable types and present a new method of input variable selection which will be compared to existing methods and demonstrated on measurements performed on a machine tool.

6

Efficient quantification of free and forced convection via the decoupling of thermo-mechanical and thermo-fluidic simulations of machine tools

Glaenzel J., Ihlenfeldt S., Naumann C., Putz M.

Journal of Machine Engineering

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2018

|

Vol. 18, No. 2

41--53

EN

Thermo-elastic deformations represent one of the main reasons for positioning errors in machine tools. Investigations of the thermo-mechanical behaviour of machine tools, especially during the design phase, rely mainly on thermo-elastic simulations. These require the knowledge of heat sources and sinks and assumptions on the heat dissipation via convection, conduction and radiation. Forced convection such as that caused by moving assemblies has both a large influence on the heat dissipation to the surrounding air. The most accurate way of taking convection into account is via computational fluid dynamics (CFD) simulations. These simulations compute heat transfer coefficients for every finite element on the machine tool surface, which can then be used as boundary conditions for accurate thermo-mechanical simulations. Transient thermo-mechanical simulations with moving assemblies thus require a CFD simulation during each time step, which is very time-consuming. This paper presents an alternative by using characteristic diagrams to interpolate the CFD simulations. The new method uses precomputed thermal coefficients of a small number of load cases as support points to estimate the convection of all relevant load cases (i.e. ambient conditions). It will be explained and demonstrated on a machine tool column.

7

Experimental study of thermal effects in cooling a circular cylinder in lock-on conditions

Gnatowski Adam, Sosnowski Marcin, Pajdak Anna, Sobczyk Jacek

Advances in Science and Technology. Research Journal

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2018

|

Vol. 12, no 2

42--51

EN

The paper presents a simple method for determining the phenomenon of unsteady thermal effects in cooling a circular cylinder. The research has been undertaken in order to explain the thermoaerodynamic processes, which are characterized by the turbulent structure of the flow around a stationary rigid heated cylinder cooled by the oscillating flow. The forced convection of heat occurs in the presence of not only random velocity fluctuation but also in the conditions of periodical forms of motion caused mainly by the process of vortex going down and externally formed oscillations of the inflow. The Nusselt number was evaluated at various frequencies of disturbances of the inlet velocity field, especially in lock-on conditions, on the surface of the circular cylinder versus angular location Θ = 0 180°. The subject of the study focuses on the analysis of current state of the problem and development of the method to measure and calculate basic values that characterize unsteady processes of thermal effects on the circular cylinder surface and indication of the directions of further work.

8

Diagnosis of Soft Spot Short Defects in Analog Circuits Considering the Thermal Behaviour of the Chip

Tadeusiewicz M., Hałgas S.

Metrology and Measurement Systems

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2016

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Vol. 23, nr 2

239--250

EN

The paper deals with fault diagnosis of nonlinear analogue integrated circuits. Soft spot short defects are analysed taking into account variations of the circuit parameters due to physical imperfections as well as self-heating of the chip. A method enabling to detect, locate and estimate the value of a spot defect has been developed. For this purpose an appropriate objective function was minimized using an optimization procedure based on the Fibonacci method. The proposed approach exploits DC measurements in the test phase, performed at a limited number of accessible points. For illustration three numerical examples are given.

9

Efekty cieplne zwilżania materiałów węglowych

Wolak E., Buczek B.

Przemysł Chemiczny

|

2015

|

T. 94, nr 2

211-214

PL

Przedstawiono wyniki pomiarów efektów cieplnych zwilżania dla różnorodnych materiałów węglowych. Na podstawie przeprowadzonych badań wyznaczono ciepło zwilżania alkoholem metylowym węgli kopalnych, węgla aktywnego oraz monolitów węglowych. W pracy dowiedziono, że efekty cieplne zwilżania zależą od rodzaju adsorbentu, jego struktury, chemicznej budowy powierzchni, rozmiaru i rodzaju porów.

EN

MeOH was adsorbed on bituminous coal, lignite, 4 C monoliths and a com. activated C in a calorimetric vessel at 20–25°C under 0.095 MPa to det. the wetting heats. The C monoliths bonded with poly(vinyl alc.) showed the highest wetting heats, while the bituminous coal the lowest one.

10

Thermal analytical winding size optimization for different conductor shapes

Wojda R. P.

Archives of Electrical Engineering

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2015

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Vol. 64, nr 2

197--214

EN

The aim of this paper is to derive an analytical equations for the temperature dependent optimum winding size of inductors conducting high frequency ac sinusoidal currents. Derived analytical equations are useful designing tool for research and development engineers because windings made of foil, square-wire, and solid-round-wire windings are considered. Temperature dependent Dowell’s equation for the ac-to-dc winding resistance ratio is given and approximated. Thermally dependent analytical equations for the optimum foil thickness, as well as valley thickness and diameter of the square-wire and solid-round-wire windings are derived from approximated thermally dependent ac-to-dc winding resistance ratios. Minimum winding ac resistance of the foil winding and local minimum of the winding ac resistance of the solid-round-wire winding are verified with Maxwell 3D Finite Element Method simulations.

11

Thermally induced damage in hexanitrohexaazaisowurtzitane

Tian Q., Yan G., Sun G., Huang C., Xie L., Chen B., Huang M., Li H., Liu X., Wang J.

Central European Journal of Energetic Materials

|

2013

|

Vol. 10, no. 3

359--369

EN

The evolution of the microstructure of hexanitrohexaazaisowurtzitane (CL-20) after a thermal stimulus plays a key role in the performance of CL-20. In the current work, microstructural variations of CL-20 caused by thermal treatment were investigated by X-ray diffraction, in situ variable-temperature optical microscopy, atom force microscopy, and small-angle X-ray scattering. A wave-like process, an abrupt volume expansion, movement, and fragmentation of CL-20 particles during phase transition were observed. After the phase transition (160 °C) the CL-20 sample acquired a very rough surface with numerous dimple depressions, and during the thermal decomposition stage (200 °C) a large number of voids were produced in both the bulk and the surface of the CL-20.

12

Temperature field analysis of optical coatings induced by millisecond and nanosecond lasers

Wang B, Qin Y, Ni X, Shen Z, Lu J, Wang X

Optica Applicata

|

2012

|

Vol. 42, nr 4

783--793

EN

To study the differences between long-pulse and short-pulse laser-induced damage in optical dielectric thin films, temperature distributions in single-layer HfO2 films, multi-layer HfO2/SiO2 films, and HfO2 films with high-absorptive inclusions induced by 1 ms and 10 ns lasers are analyzed based on the temperature field theory. Through our calculations, the damage property differences between millisecond and nanosecond lasers are summarized. The results for single-layer films show that 1 ms laser is easier to damage the substrate than 10 ns laser. For multi-layer films, the laser field effect is weaker when irradiating by 1 ms laser. Furthermore, when inclusions are introduced, the film is easier to be damaged by 10 ns laser, which means that 10 ns laser is more sensitive to the inclusions.

13

Investigation of thermal effects of water vapor adsorption on zeolites

Gwadera M., Kupiec K., Rakoczy J.

Czasopismo Techniczne. Mechanika

|

2012

|

R. 109, z. 1-M

87--94

EN

Temporal variations of temperatures in an adsorbent bed have been studied in this paper. Separation of an ethanol-water vapor mixture on zeolites has been considered. Temperature of the bed was determined both experimentally and numerically on the basis of a mathematical model of the process. The conformity between experimental and numerical values was satisfactory. It was found that maximum temperature in the bed depends mainly on water content in the raw material.

PL

W artykule podano badania czasowych zmian temperatur w złożu adsorbentu. Pomiary dotyczyły rozdzielania parowej mieszaniny etanol-woda na zeolitach. Przebiegi temperatur złoża zostały określone zarówno eksperymentalnie, jak i obliczeniowo w oparciu o model matematyczny procesu. Zgodność wyników doświadczalnych i obliczeniowych była zadowalająca. Stwierdzono, że maksymalna temperatura w złożu zależy głównie od zawartości wody w odwadnianym surowcu.

14

Efekty termiczne w ciele człowieka wywołane szybkozmiennym polem elektromagnetycznym

Przytulski A.

Pomiary Automatyka Robotyka

|

2010

|

R. 14, nr 12

145-149

PL

W artykule opisano jeden z bardziej znanych i zbadanych efektów w ciele człowieka, powodowany szybkozmiennym polem elektromagnetycznym. Wskazano na czynniki decydujące o ilości pochłanianego promieniowania, które bardzo często nie są uwzględniane przy rozpatrywaniu tego zagadnienia. Opisano następstwa efektów termicznych oraz sposoby ochrony przed mikrofalami.

EN

One of the best known and investigated effects in the human body induced by the quick-variable electromagnetic field has been described in the paper. At the same time, some factors have been shown which determine the amount of absorbed radiation but often they are not taken into consideration when this problem is being examined. The consequences of thermal effects and some possibilities for protecting people against microwaves have also been described.

15

Cyclic steady states of a thick-walled reactor with stress concentrators

Widłak G., Zieliński A.

Czasopismo Techniczne. Mechanika

|

2010

|

R. 107, z. 4-M

157-166

EN

The paper deals with elastic-plastic stress states in vicinity of a radial cross-bore in a thick-walled reactor loaded by variable internal pressure and a temperature gradient. In the description of material, the linear Prager model of hardening has been applied. The mechanism of development of reverse plastification in each load cycle has been observed. The termal effect is presented on an example of the steady stress states. The transient states (starting and closing work periods of the reactor) have been investigated in the PhD thesis of the first author.

PL

W artykule badano sprężysto-plastyczne stany naprężeń w pobliżu otworu grobościennego reaktora obciążonego zmiennym ciśnieniem wewnętrznym i różnicą temperatur. W opisie materiału stosowano liniowy model wzmocnienia Pragera. Obserwowano mechanizm rozwoju przeciwzwrotnego uplastycznienia występujący przy każdym cyklu obciążenia. Efekty termiczne pokazano na przykładzie stanów ustalonych. Stany nieustalone (rozruch i wygaszanie reaktora) były badane w ramach rozprawy doktorskiej pierwszego autora.

16

Projekt układu ASIC przeznaczonego do badania rozpływu ciepła w układach scalonych

Szermer M., Kulesza Z., Janicki M.

Mikroelektronika i Informatyka : prace naukowe

|

2007

|

Z. nr 7

69-72

PL

W celu badania zjawisk termicznych, jakie zachodzą w układach scalonych, zdecydowano się zaprojektować skład ASIC, przeznaczony specjalnie do tego celu. Układ ten będzie zawierał matryce źródeł wraz z czujnikami temperatury oraz układami sterowania i przetwarzania danych w niniejszym artykule przedstawiono koncepcję według której jest realizowany układ oraz skrócony opis komponentów w nim zawartych.

17

Modelling and analysis of selected class of switching voltage regulators with thermal effects taken into account

Posobkiewicz K.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

|

2006

|

z. 107

43-49

EN

The dissertation deals with the problem of the modelling and PSPICE-analysis of thermal effects influence on the properties of the selected switching voltage regulators with BUCK and BOOST dc-dc choppers and monolithic voltage regulators. The electrothermal macromodels of the selected monolithic voltage regulators were formulated and experimentally verified along with the proper procedure of parameters values estimation of the elaborated macro-models. The evaluation of usefulness of the elaborated macromodels for the electrothermal analysis of the selected class of switching voltage regulators as well as the investigation of the influence of self-heating on the isothermal and non-isothermal characteristics of switching voltage regulators have been performed.

PL

Praca obejmuje badania stabilizatorów impulsowych zawierających dławikowe przetwornice dc-dc typu BUCK i BOOST oraz monolityczne regulatory impulsowe. Sformułowano dla programu PSPICE oraz zweryfikowano eksperymentalnie elektrotermiczne makromodele trzech wybranych typów monolitycznych regulatorów impulsowych. Zaproponowano procedurę wyznaczania parametrów opracowanych makromodeli, dokonano oceny przydatności tych makromodeli w elektrotermicznej analizie rozważanej klasy stabilizatorów, a także zbadano wpływ samonagrzewania na nieizotermiczne charakterystyki i parametry tych stabilizatorów.

18

Adsorpcja nieizotermiczna w ziarnie kulistym

Kupiec K.

Czasopismo Techniczne. Chemia

|

2006

|

R. 103, z. 4-Ch

67-79

PL

Opracowano model adsorpcji nieizotermicznej w kulistym ziarnie, który dotyczy nieliniowych układów adsorpcyjnych. Uwzględniono występowanie oporów ruchu masy w obydwu fazach układu, przy czym opory przenoszenia masy w ziarnie są kontrolowane przez dyfuzję w porach. Przyjęto, że ciepło adsorpcji zależy od zawartości składnika w ziarnie. Równanie modelu rozwiązano analitycznie. Przeanalizowano wpływ różnych parametrów na krzywe temperaturowe adsorpcji.

EN

A new model of nonisothermal adsorption in a spherical pellet is presented. The model is applicable to systems with nonlinear adsorption isotherm. Both intraparticle and film mass transfer resistances are accounted in the model with the intraparticle mass-transfer rate beeing controlled by pore diffusion. The heat of adsorption is assumed coverage dependent. An analytical solution of the model equations has been developed. An analysis has shown the influence of various parameters on the temperature uptake curves.

19

On the thermal effects in hydrodynamic journal bearings

Fillon M.

International Journal of Applied Mechanics and Engineering

|

2005

|

Vol. 10, no 3

441-450

EN

This paper presents recent works on temperature effects in hydrodynamic journal bearings. This is an over-view of several specific thermal problems encountered particularly in fixed geometry and tilting-pad journal bearings. The temperature-viscosity variation, the heat transfer, the change in bearing clearance, the thermal and mechanical deformations, the flow regime, the transient regime, the risk of seizure, the dynamic loading as well as the misalignment are successively discussed.

20

Modelowanie efektów temperaturowych w procesach hydraulicznego szczelinowania

Szott W., Kwilosz T.

Prace Instytutu Nafty i Gazu

|

2004

|

nr 130

549

PL

Temperatura płynu szczelinującego jest jednym z podstawowych czynników determinujących jego dobór oraz podstawowe charakterystyki. Wniosek ten jest szczególnie istotny dla: powszechnie stosowanych nienewtonowskich żeli o lepkości i innych własnościach transportowych silnie zależnych od temperatury; odwiertów udostępniających formacje o temperaturze znacznie różniącej się od temperatury zatłaczanego płynu. W dotychczasowej praktyce projektowania zabiegów szczelinowania prowadzonych w szczególności przez grupę specjalistów w IGNiG nie były uwzględniane efekty zmiennej temperatury podczas zabiegu ze względu na brak efektywnych modeli pozwalających na ocenę ilościowego charakteru tego zjawiska. W pracy przeprowadzono szczegółową analizę zjawisk transportu ciepła w trakcie zabiegu hydraulicznego szczelinowania w warunkach złożowych. Sformułowano i przetestowano modele pozwalające na ilościowy opis występujących efektów. Efektem pracy jest propozycja praktycznej metody prognozowania dynamicznych zmian temperatury podczas zabiegu stymulacji odwiertu.

EN

The temperature of injection fluids used for fracturing strongly determines its effectiveness and basic characteristics. In particular, it is especially significant for: the application of non-Newtonian gels whose viscosity and other transport properties are temperature dependent, deep wells completed in rocks of elevated temperatures high above that of injected fluids. Designs of fracturing treatment performed by experts Polish Oil & Gas Institute have not take into account effects of such fluids varying temperature so far due to the lack of proper simulations tools. This paper tries to fill the gap by providing a simplified but effective software to model those thermal effects. To this aim relevant physical phenomena are analyzed, corresponding mathematical models are formed, their original solution are found and implemented in computer programs.