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Pomiary współczynnika rozszerzalności cieplnej betonu w wysokich temperaturach: porównanie metod izotermicznych i nieizotermicznych

Trník A., Medved I., Černý R.

Cement Wapno Beton

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2012

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R. 17/79, nr 6

363-372

PL

Współczynnik rozszerzalności liniowej alfa(T) betonów jest określany w zakresie temperatur 20-800°C w dwojaki sposób: w warunkach izotermicznych i liniowego wzrostu temperatury. Współczynnik ten jest w ogólnym przypadku szacowany jako pochodna temperaturowa odkształcenia termicznego mierzonego metodą dylatometryczną. Wyniki uzyskane w warunkach izotermicznych czy liniowego wzrostu temperatury są traktowane jako komplementarne. Podczas gdy w metodzie izotermicznego nagrzewu temperatura próbki wymaga długotrwałej stabilizacji, metoda liniowego wzrostu jest mniej czasochłonna i dostarcza sporej liczby punktów doświadczalnych. Jest to ważne z punktu widzenia właściwego oszacowania alfa(T) jako pochodnej odkształcenia termicznego, jak również z uwagi na możliwość zaobserwowania procesów zachodzących w próbkach podczas zmian temperatury.

EN

The linear thermal expansion coefficient, alfa(T), of several types of concrete is determined in the temperature range of 20-800°C using two different methods, namely, the isothermal and linear heating methods. The coefficient alfa(T) is in general evaluated as the temperature derivative of the thermal strain which is measured by a push-rod dilatometer. The pros and cons of the two methods are found to be complementary. While in the isothermal heating method sample temperatures are well established, the linear heating method is much less time demanding and provides a large number of experimental data. The latter is important for a proper evaluation of alfa(T) as a derivative of the thermal strain as well as tor the ability to observe processes that take place in samples as the temperature is changed.

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Ansys polyflow software use to optimize the sheet thickness distribution in thermoforming process

Pepliński K., Mozer A.

Journal of Polish CIMAC

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2011

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Vol. 6, no 3

215-220

EN

Thermoforming is a manufacturing process widely used to produce thin thermoplastic parts from small blister packs to display AAA size batteries to large skylights and aircraft interior panels. In this paper was presented numerical simulation of the inflation phase of a thermoforming process under which a thin polymer sheet is deformed into a mould under the action of applied pressure. Two cases of blowing sheet were considered. In the first, preapproved on the basis of a constant sheet temperature (T = 150°C) examined the distribution of the container wall thickness. There has been excessive thinning (about 0,2mm) in the cup corners after forming. Also simulation it was made for other constant temperature (160, 170, 180, 190 and 200°C). On this basis, was made optimization of the sheet profile temperature (in range 150÷200°C) to remove excessive thinning. Noted was a significant effect of the initial sheet temperature distribution on the final wall thickness distribution in the considered container. The Ansys Polyflow procedure of optimizing the sheet temperature distribution allowed eliminating excessive thinning in the considered cup walls corners.

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Ansys-poluflow software use to select the parison diameter and its thicknes distribution in blowing extrusion

Pepliński K., Mozer A.

Journal of Polish CIMAC

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2010

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Vol. 5, no 3

133-142

EN

The blowing extrusion in mould is one of the most widely used techniques for the production hollow plastic product example: bottle, cosmetics container, fuel tanks etc. A significant factor in the design stage of new blowing product is the selection initial parison shape in order to obtain the best distribution of final wall thickness in bottle. In this case using Ansys-Polyflow software is very helpful. This paper presents the blowing container Polyflow simulation with high-density polyethylene (Borealis, BS 2541) under isothermal and non-isothermal conditions. In the present work was showed the impact of the initial parison diameter and their geometry distribution onto final wall thickness in the sample container. This series of numerical simulation with parison optimization was showed that initial parison diameter and geometry have crucial importance for uniform final wall thickness distribution and minimal bottle mass. Eleventh cases of blowing parison were considered. Initial parison diameter was 14 mm and final 34 mm (step 2 mm). Optimizing the thirty milimeters diameter parison profile thickness for allowed to eliminate excessive thinning in the corners of container wall and get minimal container weight. An established criterion for a minimum wall thickness (1 mm) in the final product was achieved.