This study presents effects of the vane spring stiffness on frictional power characteristics of a refrigeration compressor. Comparisons on the compressor performance are investigated for different vane spring stiffnesses with compressors designed with high and low shell pressures. Results show that while compressors with a low shell pressure using a higher spring stiffness combination may reduc...

This article proposes a technique to calculate the coefficient of friction for the fingertip- object interface. Twelve subjects (6 males and 6 females) participated in two experiments. During the first experiment (the imposed displacement method), a 3-D force sensor was moved horizontally while the subjects applied a specified normal force (4 N, 8 N, 12 N) on the surface of a sensor covered wit...

A thermodynamic model describing the phase transition of first order between structure states of lubricant material in the boundary friction regime is proposed. It is shown that lubricant melts with temperature increase or at shear of rubbing surfaces if the elastic strain (stress) exceeds the critical value. The phase diagram with domains of dry and sliding friction is constructed. The depende...

Original scientific paper In this paper, the orthogonal cutting force model is proposed comprising forces due to flank wear in addition to the forces for chip formation during the hard turning of round bar made of steel 60WCrV7 hardened at 55+2HRc. Cutting force model includes two tool conditions: perfectly sharp tool with VBB = 0 and tool with maximum permissible flank wear VBBmax. Based on cu...

In this paper, by applying analytical method and using experimental method data, the effect of sliding velocity on friction coefficient for contact of copper with copper is investigated. Some equations for obtaining friction coefficient as a function of sliding velocity for contact of copper with copper by applying second analytical method and using experimental method data are achieved. The re...

The dry frictional contact between two solid surfaces is well known to obey Coulomb friction laws. In particular, the static friction force resisting the relative lateral (tangential) motion of solid surfaces, initially at rest, is known to be proportional to the normal force and independent of the area of the macroscopic surfaces in contact. Experimentally, the static friction force has been o...

To characterize the effect of shearing on function of fibrillar adhesive microstructure, friction and shear-related changes in pull-off force of a biomimetic polyvinylsiloxane mushroom-shaped fibrillar adhesive microstructure were studied. In contrast to a control flat surface, which exhibited pronounced stick-slip motion accompanied with high friction, the fibrillar microstructure demonstrated...

AIMS To measure the friction force generated during sliding mechanics with conventional, self-ligating (Damon 3 mx, Smart Clip, and Time 3) and low-friction (Synergy) brackets using different archwire diameters and ligating systems in the presence of apical and buccal malalignments of the canine. METHODS An experimental setup reproducing the right buccal segment of the maxillary arch was desi...

1. Six men and four women, 30-51 yr of age, were asked to use the tip of the washed and dried index finger to stroke six different featureless, flat surfaces mounted on a three-dimensional force platform. The six surfaces were rosin-coated glass, glass, satin-finished aluminum, poly-vinyl chloride (PVC) plastic, Teflon, and nyloprint (polyamide plastic). The subjects were requested to indicate ...

There are several parameters that have significant influence in metal forming process. One of the most important of them is friction coefficient. Friction can change the pattern of metal flow and the force needed for deformation. It is necessary to determine the friction coefficient to study the effect of friction on metal forming process. This study is concerned with numerical and experimental...