frictional shear stress is usually determined by utilizing the coefficient of friction or the constant friction factor models. the present study deals with finite element analysis of double cup extrusion process to determine the relationship between constant friction factor (m) and coefficient of friction (µ), since the metal flow in this process is very sensitive to frictional conditions. ther...

This paper presents an experimental research on the distribution of local friction factor, fb, and global friction factor, f, over the cross-section of a channel with V-shaped bottom, which typically occurs in sewers and culverts. Several series of experiments were conducted for measuring velocity and boundary shear stress. It is found that, Darcy-Weisbach, f, is more sensitive than other resis...

Frictional shear stress is usually determined by utilizing the coefficient of friction or the constant friction factor models. The present study deals with finite element analysis of double cup extrusion process to determine the relationship between constant friction factor (m) and coefficient of friction (µ), since the metal flow in this process is very sensitive to frictional conditions. Ther...

The Galerkin weighted residuals method is extended solve the laminar, fully developed flow and heat transfer of Al2O3-water nanofluid inside polygonal ducts with round corners for the constant heat flux and uniform wall temperature boundary conditions. Using the method, semi-analytical, closed-form solutions are obtained for the friction coefficient and the Nusselt number in terms of the radius...

An enhanced dynamic force model of a type of small and soft McKibben-type pneumatic muscle (PM) actuator has been developed. This model takes the factor of external loads and a more sophisticated form of friction into account, and is presented as a polynomial function of pressure, contraction length, contraction velocity and external load. The coefficients in this model are determined from a se...

Tribological conditions can change drastically during heavy loaded regimes as experienced in metal forming; this is especially critical when lubrication can only be applied at the early stage of the process because the homogeneous lubricant layer can break along the die-workpiece interface. In these cases, adopting a constant friction factor for the lubricant-surface pair may not be a valid ass...

The mechanism and geometry of force measurement with the atomic force microscope are analyzed in detail. The effective spring constant to be used in force measurement is given in terms of the cantilever spring constant. Particular attention is paid to possible dynamic effects. Theoretical calculations show that inertial effects may be neglected in most regimes, the exception being when relative...

The fundamental frictional behaviour of carbon fibre tows relevant to composite fabric forming is explored. Tow-on-tool and tow-on-tow contact are considered. For tow-on-tool contact, an experiment is devised to simultaneously observe the true filament contact length and measure the friction force over a range of normal loads. Filament contact length is not constant, as would be given from an i...

Large-eddy simulations (LES) of turbulent flow in a smoothwall pipe at Reynolds numbers based on the pipe Radius R and wall friction velocity in the range Reτ = 2,000−2,000,000 are discussed. Using a Reynolds number based on D and the bulkflow velocity, then corresponding values are ReD = 91,800 − 165,000,000. For the LES, the spectral-element code SEMTEX was used combined with the stretched-vo...