In the discrete element simulation of granular materials, the modelling of contacts is crucial for the prediction of the macroscopic material behaviour. From the tribological point of view, friction at contacts needs to be modelled carefully, as it depends on several factors, e.g. contact normal load or temperature to name only two. In discrete element method (DEM) simulations the usage of Coul...

one of the main factors that cause to quality loss for fresh fruit market apples is bruise damage. amongst the factors that affect apple sensitivity to bruising, major one is drop height and area profile during the impact. in the present study, four iranian apple varieties consisted of atirli, kapak, kowse and paiez that were selected and 100 fruits of each variety were picked up, then apples w...

Hard coatings have been adopted in cutting and forming applications for nearly two decades. The major purpose of using hard coatings is to reduce the friction coefficient between contact surfaces, to increase strength, toughness and anti-wear performance of working tools and molds, and then to obtain a smooth work surface and an increase in service life of tools and molds. In this report, we de...

The work material in metal working operations always shows some kind of anisotropy. In order to simplify the theoretical analysis, especially considering bulk deformation processes, anisotropy is usually neglected and the material is assumed to be isotropic. On the other hand, the analysis that considered the influence of anisotropy seldom incorporates the influence of friction. For predicting ...

tan films with different n2 partial pressure were deposited on 304 stainless steel using the magnetron sputtering method. the effect of gas pressure on the mechanical property, morphology and phase structure of the films is investigated by x-ray diffraction (xrd), atomic force microscopy (afm), microhardness testing, friction coefficient measurements, and wear mechanism study. the xrd results c...

This paper describes a sliding friction model for an electro-deposited coating. Reciprocating sliding tests using ball-on-flat plate test apparatus are performed to determine an evolution of the kinetic friction coefficient. The evolution of the friction coefficient is classified into the initial running-in period, steady-state sliding, and transition to higher friction. The friction coefficien...

This paper treats limit cycles caused by friction. The goal has been to explain phenomena that have been observed experimentally in mechatronic systems. Experiments have shown that oscillations of qualitatively different types can be obtained simply by changing controller specifications. Stiction is important in some cases but not in others. Necessary conditions for limit cycle are given for th...

We study the effects of temperature and sliding velocity on superlubricity in numerical simulations of the Frenkel-Kontorova model. We show that resonant excitations of the phonons in an incommensurate sliding body lead to an effective friction and to thermal equilibrium with energy distributed over the internal degrees of freedom. For finite temperature, the effective friction can be described...

Time-dependent flows of a Newtonian fluid through periodic arrays of spheres were simulated using the lattice-Boltzmann scheme. By applying a constant body force per unit mass to the fluid, a steady background fluid flow through the array of stationary spheres was first established. Subsequently, a small-amplitude perturbation to the body force, which varied periodically in time, was added and ...