Dense phase pneumatic conveying is widely used to transport granular materials or powder due to its efficiencies gained on cost and abrasion and erosion. To date these systems have been designed and analyzed using average frictional representation for the conveyed plug. This study explores the effect of this friction force by measuring strains on the pipe wall when the plug is moving passed the...

A quantitative method, using temperature-controlled friction force microscopy (FFM), has been developed to determine the frictional (dissipative) character of thin polymer films. With this method variations in friction are sampled over micrometer-scale regions and are reduced to “friction histograms,” yielding the distribution of frictional forces on the surface. The temperature dependence of 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 aim of this study was to evaluate, in vitro, frictional forces produced by ceramic brackets and arch wires of different alloys. Frictional tests were performed on three ceramic brackets: monocrystalline (Inspire ICE), polycrystalline (InVu), polycrystalline with metal slot (Clarity), and one stainless steel bracket (Dyna-Lock). Thirty brackets of each were tested, all with .022' slots, in c...

Colloidal shear thickening presents a significant challenge because the macroscopic rheology becomes increasingly controlled by the microscopic details of short ranged particle interactions in the shear thickening regime. Our measurements here of the first normal stress difference over a wide range of particle volume fractions elucidate the relative contributions from hydrodynamic lubrication a...

We model the progressive maturation of a heterogeneous mass towards a gravity-driven instability, characterized by the competition between frictional sliding and tension cracking, using array of slider blocks on an inclined basal surface, which interact via elastic-brittle springs. A realistic stateand rate-dependent friction law describes the block-surface interaction. The inner material damag...

This paper introduces an experimental technique to investigate dynamic friction characteristics of sliding interfaces at normal pressures up to 125 MPa, slip speeds up to 15 m/s and slip distances of approximately 10 mm. This new apparatus involves a novel modification of the conventional torsional Kolsky bar apparatus employed extensively in the past to investigate high-strain-rate behavior of...

STATEMENT OF THE PROBLEM Frictional forces are considered as important counterforce to orthodontic tooth movement. It is claimed that self-ligating brackets reduce the frictional forces. PURPOSE The aim of this study was to compare the resistance to sliding in metallic and clear Damon brackets with the conventional brackets in a wet condition. MATERIALS AND METHOD The samples included 4 typ...

Even though friction affects everyday life in many ways, it is still one of the biggest mysteries of physics. Friction is a truly multi-scale phenomenon with a large variety of processes acting at various length and time scales. In recent years, much attention was paid to the microand nano-scale properties of frictional interfaces in order to uncover the origins of friction. The structural aspe...