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Most dry materials in combination have friction coefficient values between 0.3 and 0.6. Values outside this range are rarer, but teflon, for example, can have a coefficient as low as 0.04. A value of zero would mean no friction at all, an elusive property. Rubber in contact with other surfaces can yield friction coefficients from 1 to 2.
Combining these four variables, a theoretical estimation of the coefficient of restitution can be made when a ball is dropped onto a surface of the same material. [9] e = coefficient of restitution; S y = dynamic yield strength (dynamic "elastic limit") E′ = effective elastic modulus; ρ = density; v = velocity at impact; μ = Poisson's ratio
Figure 1 Hard wheel rolling on and deforming a soft surface, resulting in the reaction force R from the surface having a component that opposes the motion. (W is some vertical load on the axle, F is some towing force applied to the axle, r is the wheel radius, and both friction with the ground and friction at the axle are assumed to be negligible and so are not shown.
Traction (mechanics) Traction, traction force or tractive force is a force used to generate motion between a body and a tangential surface, through the use of either dry friction or shear force. [1][2][3][4] It has important applications in vehicles, as in tractive effort. Traction can also refer to the maximum tractive force between a body and ...
Stribeck curve. The Stribeck curve is a fundamental concept in the field of tribology. It shows that friction in fluid-lubricated contacts is a non-linear function of the contact load, the lubricant viscosity and the lubricant entrainment speed. The discovery and underlying research is usually attributed to Richard Stribeck [1][2][3] and Mayo D ...
Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. [1] The fundamental objects of study in tribology ...
The capstan equation[ 1 ] or belt friction equation, also known as Euler–Eytelwein formula[ 2 ] (after Leonhard Euler and Johann Albert Eytelwein), [ 3 ] relates the hold-force to the load-force if a flexible line is wound around a cylinder (a bollard, a winch or a capstan). [ 4 ][ 1 ] It also applies for fractions of one turn as occur with ...
Friction loss is a significant engineering concern wherever fluids are made to flow, whether entirely enclosed in a pipe or duct, or with a surface open to the air. Historically, it is a concern in aqueducts of all kinds, throughout human history. It is also relevant to sewer lines.