Summary
This paper delivers tribological aspects of spherical bearings like ‘friction, wear, materials and temperature behaviour’. Effects of rolling friction, sliding friction, lubricant friction, etc. are explained. Paper includes Sample calculation for friction of a SKF bearing. Surface fatigue, abrasion, thermo-chemical reactions, adhesion are types of wears. Wear is an undesirable effect, but it is controlled by adjusting friction, materials, operating temperatures, etc. Several materials like high carbon/low carbon steel, ceramics, hard plastics, etc. used for the applications. For the analysis of temperature behaviour, Heat generations and its distributions (convection and conduction) analysed.
Friction
Friction in the spherical bearing is a resisting force (Dynamic or Kinetic or Static) between sliding or rolling contact. The effect of friction will lead to deformation, heat generation and wear on the contacting surfaces. [3]
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Due to that a Small slip occurs in the direction of rotation, which results in the deformation of the surface and to friction. This friction reduces the efficiency.
Sliding friction:
Uneven shape of the contacting area will lead to sliding friction in the bearing. Therefore, Slip velocities generated due to sliding. Lubricant properties depended upon the rate of sliding friction.
Lubricant friction:
The effect of lubrication created by the resistance of fluid properties, called lubricant friction. Viscous drag of lubricant due to viscosity, bearing speed and the amount of lubricant used, which result in the lubricant friction. [3]
Spinning Friction, Seal Friction also taken into consideration for the total friction calculation. Example for Friction Moment calculation:
[6]SKF roller bearings Selected
Diameter = 30 mm
Load = 64 KN (dynamic) = 60 KN (static)
For spherical bearings, µ =
In order to begin their outdoor adventure, a skier must first face the forces of static friction. Static friction is the force that keeps the skier at rest. As the skier overcomes the static friction there is a point where the coefficient of friction is greater than that of the kinetic friction that resists the skiers motion. It is clear to see this concept in the figure below.
When an object travels through fluid/air there are two types of flow characteristics that happen, laminar and turbulent. Laminar flow is a smooth steady flow over a smooth surface and it has little disturbance. Intuition would lead to the belief that this type of air flow would be desirable. It would make sense to assume that this smooth undisturbed air would create the least amount of resistive force due to friction. The golf ball seemingly defies this theory by traveling farther with its disruptive surface texture that creates the second flow characteristic, turbulent flow. Turbulent flow is flow that is disturbed and creates whirlpool like features. The turbulent air actually lessens the difference in velocity of the air layer that is extremely close to the ball compared to the rest of the air and so lessens the friction acting on the ball.
Tires are thrown from tires because the centrifugal force expels snow, rocks, and other foreign objects.
The frictional effects due to viscosity were taken into account by the term , where is the effective viscosity of the fluid that flowing through the porous medium and is the porosity of the medium.
Can be calculated dynamic viscosity ƞ from the kinematic viscosity μ and the density ρ according to equation (2.1.2).
Mechanical Engineering 130.2 (2008): 6 - 7. Academic Search Complete. Web. The Web. The Web.
The circle of traction is a important racing concept with applications from physics. From newtons equation f=ma we know that the more force we apply to an o...
Around the world, countries are dependent on oil and more often than not, foreign oil. The U.S. is at a time where they believe buying foreign oil supports terrorism and hurts our economy. Shale formations deep underground that spread all over the U.S. have been found to contain natural gas. This includes the Marcellus Shale formation and the Utica Shale formation, which can be found all throughout New York State and down the East Coast (Hydro-Fracking pg.1). To get at this abundance of gas underground, hydraulic fracturing was invented, but this new method of gas extraction safe for the environment and for the people around it?
Friction Stir Welding (FSW) is a solid-state joining process that involves joining of metals without fusion or filler materials. The frictional heat is produced by a rapid rotating non-consumable high strength tool pin that extends from a cylindrical shoulder. In this paper 6mm, thick copper and bronze plates are friction stir welded at different tool rotational speeds of 800, 1000 and 1200 RPM, with a constant travel speed of 40 mm/min and an axial force of 10 kN. Tests like Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Microhardness is done to identify the metallographies studies. The friction stir welding experiments are carried out with the transverse speed of 40 mm/min of the tool. Vickers hardness test, microstructure
A direct current in a set of windings creates a polar magnetic field. A torque acts on the rotor due to its relation to the external magnetic field. Just as the magnetic field of the rotor becomes fully aligned with the external magnetic field, the direction of the current in the windings on the armature reverses, thereby reversing the polarity of the rotor's electromagnetic field. A torque is once again exerted on the rotor, and it continues spinning.
Mechanochemical processes are simple, low-cost technology and environmental and the Planetary Ball Mill machine is used in this mechanochemical process. This Ball Mill machine performs as a grinding by rotating the balls and the materials inside the containers. Collision of ball can make the energy transfer from each of the ball to the sample material inside the closed container. As a result, the particle of sample size decreases due to the surface energy increase. The sample size will change and the chemical reactions also will happen in the materials where the mechanochemical reactions are happened in this stage (Hao Wu & Qiang Li, 2012). In this research, mechanical milling is being used because it refers to the milling of pure metals and compounds (P.G.McCormick & F.H.Froes,
== 1. The flywheel was set as shown with the axle of the flywheel horizontal. A polystyrene tile was placed on the floor to avoid the impact of the mass on the floor. 2. The vernier caliper was used to measure the diameter d of the axle.
where μ = the Newtonian viscosity and γ = shear rate or the rate of strain.
Knowing the information given in my introduction, I can hypothesise on two things. 1) The more paperclips there are, the greater the acceleration will be. 2) The shorter the rotor length is, the smaller the resistance will be.
The head is mounted in a “slipper” (or holder) positioned above the disk at 0.5-2.5 microns from the surface. When the disk is revolving around its axis, an air current creates a velocity gradient with the surface and air.