Flat plate skin friction calculations over a range of Mach numbers from 0.4 to 3.5 at Reynolds numbers from 16 million to 492 million using a Navier Stokes method with advanced turbulence modeling are compared with incompressible skin friction coefficient correlations. The semi-empirical correlation theories of van Driest; Cope; Winkler and Cha; and Sommer and Short T’ are used to transform the...

Measured friction coefficients of carbon nanotubes vary widely from l<0.1–l>1.0 [1–6], while theoretical studies suggest intrinsically high friction coefficients, approaching unity [7]. Here we report that measured friction coefficients of MWNT films are strong functions of surface chemistry and temperature, but are not dependent on the presence of water vapor. We hypothesize that the origin of...

Planning t>he motion of bodies in cont,act requires a model of contact rnechanics in order to predict sliding, rolling, and jamming. Such a model t'ypi-cally includes estimates of the coefficients of friction. Though, usually assumed t,o be constant, these coefficients vary and are difficult to measure. In this paper, we treat, the coefficient,s of friction as independent variables and derive r...

Silicon dioxide films are extensively used in nano and micro-electromechanical systems. Here we studied the influence of an external electric field on the mechanical properties of a SiO2 film by using nanoindentation technique of atomic force microscopy (AFM) and friction force microscopy (FFM). A giant augmentation of the relative elastic modulus was observed by increasing the localized electr...

Friction properties of carbon nanotubes have been widely studied and reported, however, the friction properties of carbon nanotubes related on state of itself. It is showing superlubricity under nanoscale, but indicates high shear adhesion as aligned carbon nanotube film. However, friction properties under high load (which is commonly in industry) of carbon nanotube films are seldom reported. I...

Large strains, anisotropy of mechanical properties of materials and Coulomb friction in contact regions are some properties in the analysis of deep drawing process. In this research, the effects of different parameters such as anisotropy coefficient, work hardening exponent and friction coefficient on deep drawing process of drawing quality steel are studied. For this purpose, the finite elemen...

Macroscopic friction coefficients observed in experiments are the result of various types of complex multiscale interactions between sliding surfaces. Therefore, there are several ways to modify them depending on the physical phenomena involved. Recently, it has been demonstrated that surface structure, e.g. artificial patterning, can be used to tune frictional properties. In this paper, we sho...

A review of the problem of aircraft skidding on Naval airfields during landings and a thorough literature search on the work conducted on friction coefficient were made. The literature search revealed that much ,vork has been conducted on basic theoretical studies of friction coefficient, on development of friction measuring devices, and on investigations to determine the factors which affect t...

agricultural crops and food materials exert frictional forces on agricultural machinery elements and on storage walls during their harvest, transportation, processing and storage. coefficient of friction is an important parameter to be predetermined in designing equipments and evaluating processes. an assessment of the coefficient of friction for agricultural materials is usually done through s...