Lubricants ordinarily operate by keeping two sliding surfaces separated. The efficiency of a lubricant may be expressed by equations of hydrodynamics where the mechanical properties of the films of lubricants are adequately defined by the properties of bulk lubricant. In the case of water lubrication of black rubber at slow speeds and low pressures the lubricating ability of water is shown to b...

Tire/road interactions play a critical role in safe operation of ground vehicles. This paper presents the modeling, analysis, and experimental studies of stick–slip interactions between the stationary tire and the firm road. A semi-analytical model is first proposed to predict the normal force distribution on the tire contact patch. A beam–spring network modeling approach is then used to captur...

The variation of the monomeric friction coefficient of styrene butadiene copolymer (SBR) and natural rubber (NR) with various degrees of cure was analyzed. Samples with different levels of cure were prepared. Loss tangent measurements of the samples were performed by means of a damped torsion pendulum between 173 K and 373 K. Data were analyzed in the frame of the Kloczkowsky, Mark and Frisch m...

in this study, some seed physical properties of two sugar beet varieties, shirin and gadouk (436), were evaluated as a function of moisture content. physical properties included length, width, thickness, arithmetic and geometric mean diameters, sphericity, thousand seed weight, angle of repose, terminal velocity, true density, bulk density, porosity, and coefficient of friction. four moisture c...

In 1883 Johannes von Kries published the theory of waterhammer in a study of blood flow in arteries. He derived the “Joukowsky formula” before Joukowsky (1898) and Frizell (1898) did. He considered skin friction in unsteady laminar flow and thus derived formulas for wave attenuation and line pack. The theory was confirmed by experimental results obtained in rubber hoses. In 1892 he published th...

Rolling friction has been explained in terms of crack propagation through an adhesive joint. The contact between a smooth cylinder and flat has been regarded as an adhesive junction bounded by two cracks moving in the same direction at the same speed, one crack continually opening and one closing. Propagation of these cracks requires a force which is calculated from crack theory and shown to be...

The viscoelastic deformation of tire rubber by road surface asperities was modeled by the rolling contact between a Kelvin solid and a surface motif, which is the part of surface profiles between two peaks. Stress and strain calculations showed that contact losses might occur locally, depending on the rolling speed, the viscoelastic properties of the Kelvin solid and the geometry of the motif. ...