Wyniki wyszukiwania - BazTech

1

Comparison of off -line, on-line and in-line measuring techniques used for determining the rheological characteristics of polyethylene composites with calcium carbonate

Klozinski Arkadiusz, Barczewski Mateusz

Polimery

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2019

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T. 64, nr 2

83--92

EN

The article has presented comparative tests of the rheological characteristics of lowdensity polyethylene (LDPE) with an addition of calcium carbonate (CaCO3), containing 7, 14, 21 and 28 wt % of filler, respectively. The measurements were carried out by an off -line measuring technique (using a modified dead-weight plastometer), an on-line measuring technique (with a gear pump capillary rheometer) and an in-line measuring technique (with an extruder rheometer). The rheological parameters of the polymeric materials were determined based on the Ostwald de Waele powerlaw model at a temperature of 170 °C. The effect of calcium carbonate addition on the characteristic of operation of each of the employed instruments, the flow curves, the viscosity curves, and the values of power-law index (n) and consistency factor (K) have been determined.

PL

Przedstawiono badania porównawcze charakterystyk reologicznych kompozytów polietylenu małej gęstości (LDPE) z dodatkiem 7, 14, 21 i 28 % mas. węglanu wapnia (CaCO3). Zastosowano techniki pomiarowe typu off-line (zmodyfikowany plastometr obciążnikowy), on-line (reometr kapilarny z pompą zębatą) oraz in-line (reometr wytłaczarkowy). Parametry reologiczne materiałów polimerowych wyznaczano w temperaturze170 °C na podstawie modelu potęgowego Ostwalda-de-Waele. Określano wpływ dodatku węglanu wapnia na charakterystykę pracy każdego z zastosowanych urządzeń, przebieg krzywych płynięcia, przebieg krzywych lepkości oraz wartości wykładnika płynięcia (n) i współczynnika konsystencji (K).

2

Identification of the Process of Dynamic Stretching of Threads in Warp-Knitting Technology

Prążyńska A., Mikołajczyk Z.

Autex Research Journal

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2017

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Vol. 17, no. 4

334--343

EN

The publication presents a theoretical study of the susceptibility of rheological models of threads to dynamic stretching in the context of modern, highly efficient textile technologies. Input parameters of the four analyzed models, the Kelvin-Voigt model, the Maxwell model, Standard model 2, and the Zener model, corresponded to the actual values of the coefficients of viscosity, elasticity, kinematic and dynamic loading, and stretching speed for the analyzed polyester silk threads produced in a knitting process, with knitting speeds from 700 to 1,600 courses/min. The research proves that the tested thread models behave differently in the stretching process-the Kelvin-Voigt model is sensitive to both the increases in kinematic loading and viscosity coefficient, Standard model 2 is only susceptible to dynamic stiffness, and the Zener model is significantly sensitive to kinematic loading. All responses of the models increase with the increase in stretching speeds. The obtained results indicate substantial “accuracy tolerance” in setting input parameters while identifying dynamics of the knitting process on warp-knitting machines.

3

MHD flow of longitudinal and torsional oscillations of a circular cylinder with suction in a couple stress fluid

Nagaraju G., Ramana Marthy J. V.

International Journal of Applied Mechanics and Engineering

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2013

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Vol. 18, no. 4

1099--1114

EN

In this paper, we consider the flow an incompressible electrically conducting couple stress fluid generated by performing longitudinal and torsional oscillations of a porous circular cylinder subjected to constant suction/injection at the surface of the cylinder and in the presence of a radial magnetic field. A finite difference method is proposed to analyze the velocity components, in an infinite expansion of a couple stress fluid under vanishing couple stresses on the boundary. The effects of the magnetic parameter, couple stress parameter, Reynolds number, the ratio of couple stress viscosities parameter and suction parameter on velocity components and drag are discussed and shown graphically.

4

Experimental solution for viscosity coefficient of solid alloy material

Luo Y. S., Dohda K., Wang Z.

International Journal of Applied Mechanics and Engineering

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2003

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Vol. 8, no spec.

271-276

EN

This paper deals with the experimental method and solution for viscosity coefficient of solid alloy materials, such as, solid aluminum alloy Lc4. Standard creep specimen of f10mm with male screw ends were adopted, and groups of creep tests were carried out under high-temperature on RD2-3 type creep-machines. Tests under a constant temperature but different stress levels, and under a constant stress but different temperature levels were carried out. The effects of temperature and stress on strain and strain rate were analyzed. By putting the experimental data into the constitutive equation of the rheological model of viscoplastic material, the viscosity coefficients of the solid alloy materials under different temperature levels and stress levels were derived easily. They are similar to viscosity coefficient of non-Newtonian fluid. This experiment is simply to be operated, and the calculation is conveniently to be solved.