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Modelling of Heat Transfer at the Solid to Solid Interface

Rywotycki M., Malinowski Z., Falkus J., Sołek K., Szajding A., Miłkowska-Piszczek K.

Archives of Metallurgy and Materials

2016

Vol. 61, iss. 1

341--346

In technological process of steel industry heat transfer is a very important factor. Heat transfer plays an essential role especially in rolling and forging processes. Heat flux between a tool and work piece is a function of temperature, pressure and time. A methodology for the determination of the heat transfer at solid to solid interface has been developed. It involves physical experiment and numerical methods. The first one requires measurements of the temperature variations at specified points in the two samples brought into contact. Samples made of C45 and NC6 steels have been employed in physical experiment. One of the samples was heated to an initial temperature of: 800°C, 1000°C and 1100°C. The second sample has been kept at room temperature. The numerical part makes use of the inverse method for calculating the heat flux and at the interface. The method involves the temperature field simulation in the axially symmetrical samples. The objective function is bulled up as a dimensionless error norm between measured and computed temperatures. The variable metric method is employed in the objective function minimization. The heat transfer coefficient variation in time at the boundary surface is approximated by cubic spline functions. The influence of pressure and temperature on the heat flux has been analysed. The problem has been solved by applying the inverse procedure and finite element method for the temperature field simulations. The self-developed software has been used. The simulation results, along with their analysis, have been presented.

Właściwości dielektryczne modyfikowanych poliimidów z zawartością węgla C60

Subocz J., Valozhyn A.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

2003

Vol. 38, nr 13

75-78

Przedstawiono wyniki badań wpływu modyfikacji poliimidu na relaksację dielektryczną. Stwierdzono, że dodatek węgla C60 nie wprowadza zmian w naturze beta-relaksacji, natomiast zmniejsza przenikalność dielektryczną. Analiza przy pomocy równania H-N sugeruje, że wskutek obecności fullerenów zachodzi generacja ładunku na granicy faz. Fullereny zapełniają wolne przestrzenie i powodują ograniczenie strat dielektrycznych.

The article presents the test results concerning the effect carbon C60 filler of elec. properties of filled Kapton and Upilex polyimides. The result showed that addn. of C60 carbon does not cause changes in beta-relaxation characteristics, however it reduces their dielec. permittivity. The anal. made through applying the H-N equation suggested that the presence of fullerenes in polyimides causes generation of a charge on the phase boundary. The fullerenes occupy free spaces that results in dielec. loss redn.