A. Walicka

Bio: A. Walicka is an academic researcher from University of Zielona Góra. The author has contributed to research in topics: Bearing (mechanical) & Thrust bearing. The author has an hindex of 9, co-authored 90 publications receiving 346 citations.

Mathematical modelling of some biological bearings

Abstract: Couple stresses affect lubrication problems when additives are used or the lubricant contains long-chain molecules. Such couple stresses may have a significant effect on the behaviour of bearings in practice. The effect of couple stresses with and without rotational inertia on mechanical parameters of the curvilinear thrust bearing is considered. As an example we discuss simulation of the squeeze-film behaviour of a human joint modelled as a hemispherical nonspinning bearing. It is shown that the influence of couple stresses on the characteristics of the bearing discussed is significant and not negligible. The effects of couple stresses provide an enhancement in the pressure distribution and of the load-carrying capacity.

The Rotating Flow of Magneto Hydrodynamic Carbon Nanotubes over a Stretching Sheet with the Impact of Non-Linear Thermal Radiation and Heat Generation/Absorption

Abstract: The aim of this research work is to investigate the innovative concept of magnetohydrodynamic (MHD) three-dimensional rotational flow of nanoparticles (single-walled carbon nanotubes and multi-walled carbon nanotubes). This flow occurs in the presence of non-linear thermal radiation along with heat generation or absorption based on the Casson fluid model over a stretching sheet. Three common types of liquids (water, engine oil, and kerosene oil) are proposed as a base liquid for these carbon nanotubes (CNTs). The formulation of the problem is based upon the basic equation of the Casson fluid model to describe the non-Newtonian behavior. By implementing the suitable non-dimensional conditions, the model system of equations is altered to provide an appropriate non-dimensional nature. The extremely productive Homotopy Asymptotic Method (HAM) is developed to solve the model equations for velocity and temperature distributions, and a graphical presentation is provided. The influences of conspicuous physical variables on the velocity and temperature distributions are described and discussed using graphs. Moreover, skin fraction coefficient and heat transfer rate (Nusselt number) are tabulated for several values of relevant variables. For ease of comprehension, physical representations of embedded parameters such as radiation parameter ( R d ) , magnetic parameter ( M ) , rotation parameter ( K ), Prandtl number ( P r ), Biot number ( λ ) , and heat generation or absorption parameter ( Q h ) are plotted and deliberated graphically.

Ein Gedankenmodell zur kinetischen Theorie der festen Körper

Abstract: Wenn man den Zusammenhang der Spannungen und Formanderungen bei einem Festigkeitsversuch naher untersucht, so zeigt sich, das man neben einem umkehrbaren Anteil mehrere nicht umkehrbare Anteile unterscheiden kann. Der umkehrbare Anteil ist dasselbe, was man auch als rein elastischen Anteil bezeichnet; bei den nicht umkehrbaren Anteilen ist einer, der von den Belastungsfolgen abhangt, nicht aber von der darauf verwandten Zeit, und ein anderer, der eine deutliche Zeitabhangigkeit zeigt. Der erstere wird in Analogie zu einer ahnlichen Erscheinung beim Magnetisieren von Eisen und Stahl elastische Hysteresis genannt, der zweite, die Zeitwirkung, umfast die Erscheinungsgruppe der elastischen Nachwirkung, die Abhangigkeit der Fliesspannung von der Streckgeschwindigkeit und auch gewisse langsame Zustandsanderungen, die in Veranderungen der Fliesgrenze bestehenl.