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1

Effect of low-pressure plasma treatment on the thermal behaviour of organo-modified montmorillonite nanoclay

Almansoori A., Alkaron W.

Archives of Materials Science and Engineering

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2024

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Vol. 125, nr 1

5--14

EN

Purpose: The thermal behaviour of nanoclay can be considered an important factor in obtaining high-performance polymer nanocomposite. Thus, the current study aims to investigate the effect of plasma treatment on the thermal stability of two organically modified nanoclays, Cloisite 30B (C30B) and Nanomer I.34TCN (I.34TCN), compared with pristine NaMMT. Design/methodology/approach: The nanoclays were studied and characterised using Thermogravimetric Analysis (TGA). TGA was used to measure the weight loss of the plasma-treated and untreated nanoclays (C30B, I.34TCN, and NaMMT nanoclays) over a 30-630 C temperature range. Findings: Based on TGA results, the decomposition of all plasma-treated nano clays (C30B, I.34TCN and pristine NaMMT) was shifted to a lower temperature than in the untreated ones at all those stages. Thus, plasma treatment was successfully used as a convenient method to alter the chemical structure and surface morphology of MMT nanoclays for better thermal behaviour and filling distribution. Research limitations/implications: This hypothesis can be corroborated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) for a better understanding of the structural and surface changes that occurred due to the plasma action, which can provide an interpretation of the changes in the thermal behaviour of nanoclays. Practical implications: The plasma treatment, therefore, can improve the thermal stabilisation of the nanocomposite powders for the LS fabricated parts and even for the surrounding powder for the recovery process. Plasma-treated nano clay, therefore, can be used to reinforce polymers with an expectation of increasing the thermal stability of the resultant composites. Thus, the plasma-treated composite can be fabricated for laser sintering applications in fields that require high thermal stability. Originality/value: The surface modification of nanoclay powders via plasma treatment can be used as a convenient method to alter the chemical structure and surface morphology for better thermal behaviour and filling distribution.

2

A comprehensive review of polymer materials and selective laser sintering technology for 3D printing

Jabri F. E., Ouballouch A., Lasri L., Alaiji R. El

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 118, nr 1

5--17

EN

Purpose: This review analyses different approaches used to study selective laser sintering (SLS) technology of polymer materials. These main approaches concern: thermal behaviour, fatigue and surface roughness. Design/methodology/approach: Regarding the first behaviour, researchers extensively studied the impact of process parameters, including scan speed, laser, power and laser energy density, on the thermal behaviour of 3D printed parts. Numerical and experimental analyses are used to conduct process parameter evaluations. Findings: Laser power and scan speed are the most significant parameters of the laser energy density. For the second, according to test protocols and quantitative analysis performed, the authors concluded that the combination of small and large laser energy density particles generates higher sintering and better fatigue resistance. Moreover, tensile analysis in different environments showed that testing in the water decreased the fatigue life of polymer samples. The influence of process parameters on the mechanical properties and surface roughness of 3D parts is also analysed. In addition, the investigators found that the additives increase the surface roughness of 3D printed parts. Practical implications: This review shows that researchers can focus on creating a combination of these approaches to expand the use of this process for industrial part production. Originality/value: All these investigations have made it possible to determine the optimal process conditions to ensure higher quality, optimal surface quality and better fatigue strength.

3

The peculiarities of applying CAD/CAE systems for the primary combustion chamber flame tube cycle life prolongation of the tactical military aircraft afterburning turbofan jet engine

Pashchenko Serhii, Kharchenko Oleksandr, Shulhin Artem, Chemerys Yevheniy

Journal of KONBiN

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2022

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Vol. 52, iss. 4

167--176

EN

In this article, the computational simulation of the workflow in the primary combustion chamber flame tube of the afterburning turbofan jet engine (ATJE) on the tactical military aircraft was carried out. The geometric model of a flame tube was created and adapted to perform the interrelated calculation of the thermal and stress-strain behaviour of the walls of the flame tube influenced by the operational loads during the computational simulation of the workflow. Quantitative and qualitative analysis of the simulation results was conducted, and the connection between the peculiarities of the workflow and the characteristic damage of the flame tubes, detected during the operation, was established. The possibility of using modern CAD/CAE systems to solve the scientific tasks towards maximizing the cycle life potential of the main and primarily important components of the ATJE on the assessment basis of their damage exhaustion degree was determined.

4

Thermogravimetric Study of Ionic Pt(II) Complexes Containing Bis(diphenylthiophosphinyl)methane

Dogan F., Irisli S.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 1

1-6

EN

The TG-DTG and DTA study of dipositive platinum(II) complexes of the general formula [Pt(L-L)(dppmS2)](ClO4)2, where dppmS2 = Ph2P(S)CH2P(S)Ph2 and L-L = dppm (Ph2PCH2PPh2), dppe (Ph2PCH2CH2PPh2), and dppp (Ph2PCH2CH2CH2PPh2), were studied by thermogravimetric analysis from ambient temperature to 1000 graduate C in nitrogen atmosphere. The decomposition occurred in one stage for [Pt(L-L)dppmS2](ClO4)2, [Pt(L-L)dpppS2](ClO4)2 and [Pt(L-L)dppmS2](ClO4)2 complexes. The values of activation energy, E, frequency factor, A, reaction order, n, entropy change, delta S Not equal to , enthalpy change, delta H Not equal to , and Gibss free energy change, delta G Not equal to , of the thermal decomposition were calculated by means of Coats-Redfern method (CR), MacCallum-Tanner method (MC) and van Krevelen method (vK). The activation energy values obtained by CR, MC and vK methods were in good agreement with each other.

5

A study on thermal behaviour of curved steel box girder bridges considering solar radiation

Kim S. H., Cho K. I., Won J. H.

Archives of Civil and Mechanical Engineering

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2009

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Vol. 9, no 3

59-76

EN

Solar radiation induces non-uniform temperature distribution in the bridge structure depending on the shape of the structure and shadows cast on it. Especially in the case of curved steel box girder bridges, nonuniform temperature distribution caused by solar radiation may lead to unusual load effects enough to damage the support or even topple the whole curved bridge structure if not designed properly. At present, it is very difficult to design bridges in relation to solar radiation because it is not known exactly how varying temperature distribution affects bridges; at least not specific enough for adoption in design. Standard regulations related to this matter are likewise not complete. In this study, the thermal behavior of curved steel box girder bridges is analyzed while taking the solar radiation effect into consideration. For the analysis, a method of predicting the 3-dimensional temperature distribution of curved bridges is used. It uses a theoretical solar radiation energy equation together with a commercial FEM program. The behavior of the curved steel box girder bridges is examined using the developed method, while taking into consideration the diverse range of bridge azimuth angles and radii. This study also provides reference data for the thermal design of curved steel box girder bridges under solar radiation, which can be used to develop design guidelines.

PL

Promieniowanie słoneczne powoduje niejednorodny rozkład temperatury w konstrukcji mostu i zależny od jego kształtu oraz padających cieni. Szczególnie w przypadku mostów zakrzywionych ze stalowych dźwigarów skrzynkowych niejednorodny rozkład temperatur wywołany promieniowaniem słonecznym może prowadzić do powstania wyjątkowych sił wystarczających do zniszczenia podpór lub nawet zniszczenia mostu, o ile jego konstrukcja nośna nie została odpowiednio zaprojektowana. Obecnie projektowanie mostów z uwzględnieniem promieniowania słonecznego jest bardzo trudne, ponieważ wpływ zmiennego rozkładu temperatury na konstrukcję mostu nie jest dokładnie znany, jak również nie jest określony sposób uwzględnienia tych wpływów w projektowaniu. Nie istnieją również żadne normy dotyczące tego zagadnienia. W pracy przedstawiono analizę zachowania mostu uwzględniającą działanie promieniowania słonecznego. Do analizy użyto metodę przewidywania trójwymiarowego rozkłady temperatury w mostach zakrzywionych w planie. W metodzie tej wykorzystane zostało teoretyczne równanie promieniowania słonecznego oraz program do analizy metodą elementów skończonych. Przeprowadzono badania zachowania mostu przy uwzględnieniu różnych zakresów kąta azymutu oraz promieni zakrzywienia mostu. Praca stanowi źródło - możliwych do wykorzystania w projektowaniu - informacji dotyczących zagadnień termicznych w mostach zakrzywionych o przęsłach ze stalowych dźwigarów skrzynkowych pod wpływem promieniowania słonecznego.

6

FEM- based thermal modelling of the cutting process using power law-temperature dependent concept

Grzesik W., Niesłony P.

Archives of Materials Science and Engineering

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2008

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Vol. 29, nr 2

105-108

EN

Purpose: Purpose of this study is to compare two variants of the FEM simulation model of orthogonal cutting process of AISI 1045 carbon steel with uncoated and multilayer-coated carbide tools i.e. standard and Power Law–Temperature Dependent (PL-TD) options. The primary reason for undertaking this problem was unsatisfactory accuracy of the predictions of cutting temperature especially for coated cutting tools. Design/methodology/approach: Methodology used employs the Lagrangian-FEM model with more accurate thermophysical properties of the substrate and coating materials. All thermal properties (thermal conductivity and diffusivity and specific heat) are expressed in the forms of polynomial models of the 5th degree. Multi-layer coating is substituted by homogeneous monolithic layer with equivalent thermal properties. In addition, these simulation algorithms use the Johnson-Cook constitutive law. Findings: Basically, the FEM package applied allows the temperature distribution and heat flux intensity to be predicted closer to appropriate measurements and computations. Research limitations/implications: Research limitations deal with the lack of reliable data and models for both cutting tool and workpiece material. Future research should be focused on other coatings which are commonly used in cutting tool industry. Practical implications: They can be related to more detailed inputs from research and developing centers which exist in many leading branches of industry. Unfortunately, academic approach is sometimes very narrow and does not consider real machining conditions. Originality/value: Originality of this simulation approach can be seen in elaborating more accurate models for thermal properties. Moreover, it contributes to finding some fundamental relationships between all physical phenomena involved into tool-chip contact behaviour.

7

Thermal modelling of the cutting process using FEM simulation with updated thermophysical properties of tool materials

Niesłony P.

Advances in Manufacturing Science and Technology

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2008

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Vol. 32, nr 3

15-25

EN

This study compares two variants of the FEM simulation model of orthogonal cutting process of C45 carbon steel with multilayer-coated tools. In particular, new data on the thermophysical properties of the substrate and coating materials, measured by means of the advanced Laser Flash and Differential Scanning Calorimeter methods, were applied. Both simulation algorithms use the Power Law constitutive model, similar to the Johnson-Cook law but the second variant, termed Power Law' Temperature Dependent (PL-TD) algorithm, takes into account the temperature-dependent thermophysical properties of the tool. In this study, the temperature distribution, heat flux intensity and tool-chip contact length were validated based on the appropriate measurements.

PL

W artykule porównano dwa warianty symulacyjne modelu MES procesu ortogonalnego skrawania stali węglowej C45 narzędziem z powłoką wielowarstwową. Wprowadzono nowe dane cieplnofizycznych właściwości materiału substratu i powłoki określone zaawansowanymi metodami różnicowej kalorymetrii skaningowej oraz Laser-Flash. Oba zastosowane algorytmy symulacji wykorzystują wykładniczy model konstytutywny, zbliżony do modelu Johnsona-Cooka. Drugi wariant, określany Power Law-Temperature Dependent (PL-TD), uwzględnia zależne od temperatury właściwości cieplnofizyczne materiału narzędzia. W prowadzonych badaniach rozkład temperatury, intensywność strumieni ciepła oraz długość kontaktu wiór-ostrze zweryfikowano w oparciu o uzyskane wyniki pomiarowe.

8

Improved prediction of temperature distribution in power transformers.

Wemlader A., Tenbohlen S.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2007

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Vol. 46, nr 19

278-281

EN

In modern development of transformers there is a strong requirement for a save thermal calculation on the one hand and - on the other hand not to use more material and further resources than necessary. These aims can only be achieved by a precise calculation of the temperature distribution in the windings. The conventional way of calculating the temperature distribution is to calculate the bulk temperature of the oil in the winding channels by the known losses, the flow rate and the heat capacity of the oil. The temperature in the solid insulation is further calculated by an assumed heat transfer coefficient which is in reality known only very roughly. The topic of this article is a more precise alternative way of calculating the temperature distribution by first calculating the flow field by CFD (Computational Fluid Dynamics) models and therefore get a much more accurate value for the local heat-transfer coefficient between oil and solid insulation.

9

Precise modelling of HSC machine tool thermal behaviour

Jędrzejewski J., Modrzycki W., Kowal Z., Kwaśny W., Winiarski Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

245-252

EN

Purpose: The development of precision machine tools requires modelling, simulation and optimization, especially the accurate modelling of machine tool thermal behaviour aimed at improving the machine tool design. Design/methodology/approach: This paper discusses machine tool design improvement based on thermal behaviour modelling and the complexities involved. A highly accurate thermal model of the HSC machine tool is presented and the necessity of including the whole complex of factors affecting machine tool behaviour and error compensation is highlighted. Modelling problems are illustrated with examples of accurate modelling and simulation of machine tool behaviour, aimed at minimizing thermal disturbances in machining precision. Findings: The precise modelling of HSC machine tools dynamic spindle displacement during a change of rotational speed. Research limitations/implications: The transitional states of spindle speed changes are very complex and difficult to precise recognition. Practical implications: The need of integrated complex modelling of precise HSC machine tools thermal behaviour. Originality/value: All models used for machine tool behaviour simulation are fully original.

10

A study on thermal behaviour of HDPE/CaCO3 nanocomposites

Zebarjad S. M., Sajjadi S. A., Tahani M., Lazzeri A.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

173--176

EN

Purpose: In order to improve physical and mechanical properties of high density polyethylene (HDPE) addition of filler, rigid particles and even elastomer to HDPE is very common. One of the most important filler which is added to it is nano size calcium carbonate (CaCO3). To avoid agglomeration of nano size calcium carbonate addition of fatty acids such as stearic acid is very common. Design/methodology/approach: In the current study, nanocomposites with 10vol% nano size calcium carbonate were prepared. To investigate the role of stearic acid on nanocomposite behaviour, nanoparticles were coated at different stearic acid content. Thermal behaviour of high density polyethylene and its nanocomposites reinforced with both uncoated and coated calcium carbonate were investigated. For this purpose differential scanning calorimetry (DSC) test was used. Findings: The results of DSC test showed that addition of 10vol% calcium carbonate to HDPE causes a slightly rise in its melting point but stearic acid content has no significant effect on the melting temperature of HDPE nanocomposites. Research limitations/implications: Agglomeration of nanosized calcium carbonate during sample preparation was the major research limitation. Originality/value: Crystallization temperature of HDPE with addition of 10vol% calcium carbonate increases, while addition of stearic acid causes to decrease it. Both stearic acid content and 10vol% calcium carbonate have no significant effect on crystallinity index of HDPE.

11

Nanostructure and Thermal Behaviour of Isotactic Polypropylene

Janicki J.

Fibres & Textiles in Eastern Europe

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2002

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Vol. 8, no. 1 (36)

62--65

EN

The nonisothermal melting and crystallisation process of isotactic polypropylene was investigated by time-resolved simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction methods with synchrotron radiation. It was found that the nanostructure of the iPP investigated depends on thermal conditions. The nanostructure can be described based on parameters determined from one-dimensional correlation function analysis. It was shown that real-time synchrotron investigation is an appropriate method for describing changes of supermolecular structure parameters during crystallisation and melting process. Changes of long period values, degree of crystallinity, invariant, thickness of crystalline lamellae and thickness of amorphous layers during heating and cooling on wide range of temperature were discussed.

PL

Nieizotermiczne topnienie i proces krystalizacji izotaktycznego polipropylenu badano metodą oznaczenia równoczesnego rozkładów czasowych niskokątowego rozproszenia promieniowania rentgenowskiego (SAKS) oraz metodą szerokokątowej dyfrakcji promieniowania rentgenowskiego z promieniowania synchrotronowego. Stwierdzono, że nanostruktura badanego izotaktycznego polipropylenu zależy od warunków termicznych. Nanostruktura może być opisana na podstawie parametrów wyznaczonych z analizy funkcyjnej korelacji liniowej. Wykazano, że badania synchrotronowe w czasie rzeczywistym są odpowiednią metodą dla opisania parametrów nadmolekularnej struktury podczas krystalizacji i procesu topnienia. Przeprowadzono dyskusję na temat zmian długiego okresu, stopnia krystalizacji, niezmienników, grubości krystalicznych lameli i grubości warstw amorficznych podczas grzania i chłodzenia w szerokim zakresie temperatur.

12

Measuring flax elementarisation

Castellar de M. D., Ussman M., Bosch T., Manich A. M.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2000

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z. 59

211-217

EN

Flax fibres from Celitex have been obtained using a conventional line in Spain. Measurements have been made after tearing and carding. The same fibre has been processed in the Technical University of Lodz and measurements have been made also after tearing, carding and cottonized fibre. Values of fineness and length measured using Image analysis, water absorption and thermal behaviour by DSC are reported on this paper. Some relationships are studied.