Contact area

About: Contact area is a research topic. Over the lifetime, 12358 publications have been published within this topic receiving 256401 citations. The topic is also known as: contact patch & contact region.

Analysis of Contact Phenomena and Heat Exchange in the Cutting Zone Under Minimum Quantity Cooling Lubrication conditions

Abstract: The paper critically investigates about the influ- ence of emulsion mist cooling on the conditions of heat absorption from the machining zone. The cooling conditions under which the total number of drops falling on the hot sur- faces of the machining zone evaporate have been studied. The state of cutting wedges made of P25 sintered carbide after finish turning of two-phase pearlite-ferrite AISI 1045 steel with the presence of an anti-seizure and anti-wear addi- tive has been subjected to scanning inspection. In the contact area, the content of surface active compounds is much larger as compared to the areas beyond the contact. It has been observed that the concentration of active compounds on the

Normal Vibrations and Friction Under Harmonic Loads: Part II—Rough Planar Contacts

Abstract: Nonlinear normal contact vibrations, excited by the application of a dynamic normal load to the contact region formed between rough surfaces, are studied using the method of multiple scales. The planar rough surface is described by the Greenwood and Williamson model. The contact region behaves as a nonlinear spring in parallel with a viscous damper, and supports a rigid mass. It is shown that the average contact separation in the presence of dynamic loading is greater than the static separation under the same average load. In contrast to some previous results, this increase in average separation does not result in a significant change in the average friction force.

The Kinetic Friction on Snow and Ice

Abstract: This paper presents many experimental data of friction between a slider and snow or ice in relation to ski-ing and skating. Measurements of the kinetic coefficient of friction μk for a metallic or plastic-resin ring in contact with a snow surface were made using an oscillograph. The mechanism of this friction was analysed through oscillograms showing frictional resistance between a slider and a snow surface together with observations of the real contact area between the surface of the slider and snow grains. It was shown that friction at low sliding speeds caused plastic deformation within snow, but, when sliding velocity was increased, a stick-slip friction occurred accompanying fractures and abrasions of snow grains. Since the laboratory experiment of friction on snow is limited to a range of low sliding speeds, the measurements of μk for high sliding velocities were made by the use of practical skis. The value of μK for practical skis increased from 0.03 to 0.1 as the speed increased from for velocities 5 to 22 m/s.The measurements μk for skates were made using a specially designed device on skating rinks prepared both on natural lake ice and artificial ice. The temperature dependence of μk was studied for the blades of skates; μk showed a minimum value for both rinks around —1 to — °C, namely, 0.003 for the natural lake ice and 0.007 8 for the artificial rink ice.

Contact and friction of nanoasperities: effects of adsorbed monolayers.

Abstract: Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, and spherical tip with radius of order 30 nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare surfaces showed that the atomic scale deviations from a sphere that are present on any tip constructed from discrete atoms lead to significant deviations from continuum theory and dramatic variability in friction forces. Introducing an adsorbed monolayer leads to larger deviations from continuum theory but decreases the variations between tips with different atomic structure. Although the film is fluid, it remains in the contact and behaves qualitatively like a thin elastic coating except for certain tips at high loads. Measures of the contact area based on the moments or outer limits of the pressure distribution and on counting contacting atoms are compared. The number of tip atoms making contact during a time interval $\ensuremath{\Delta}t$ grows as a power of $\ensuremath{\Delta}t$ when the film is present and as the logarithm of $\ensuremath{\Delta}t$ for bare surfaces. Friction is measured by displacing the tip at a constant velocity or pulling the tip with a spring. Both static and kinetic friction rise linearly with load at small loads. Transitions in the state of the film lead to nonlinear behavior at large loads. The friction is less clearly correlated with contact area than load.