Equal channel angular pressing is the most promising method of severe plastic deformation with the capability of producing ultrafine grained materials. These materials exhibit improved mechanical and physical properties compared with their coarse grained counter parts.The temperature variation in the sample during ECA-pressing is a key factor determining the final microstructure and mechanical ...

Nanoparticles of transition metal dichalcogenides (TMDC) have been known to reduce friction and wear when added to oil-type liquid lubricants. Aggregation limits the ability of the nanoparticles to penetrate into the interface between the two rubbing surfaces—an important factor in friction reduction mechanisms. Doping has been successfully used to reduce agglomeration, but it must be done in t...

A modified model for predicting the friction force between drill-string and borehole wall under in-plane vibrations was developed. It was found that the frictional coefficient in sliding direction decreased significantly after applying in-plane vibration on the bottom specimen. The friction reduction is due to the direction change of friction force, elastic deformation of surface asperities and...

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...

Three important parameters in designing a closed die for forging process are ratio of width to flash thickness, ratio of  height to billet diameter and the friction factor. In this paper the influences of these parameters on the required force for the forging and percentage of die filling were investigated. It was found that by controlling the flash dimension, the material loss is reduced and t...

a study on the evaluating equivalent damping and response modification factors of frames equipped by pall friction dampers is presented. to do so, buildings with various stories were considered. nonlinear and linear dynamic time history analysis has been performed to evaluate equivalent damping for pall friction dampers. ground motions with various frequency characteristics scaled with iranian ...