Friction, Mechanical Engineering

FRICTION:

you have learnt laws of friction and problems involving dry friction. The relative sliding motion of one body on another body is resisted by forces called as friction forces. The sense of these friction forces is such as to oppose the impending or real sliding motion. While there is no impending motion, the friction forces should be found by using the equations of static equilibrium. The limiting static friction is attained when relative sliding motion of the surface is impending and is given by following :

                                                            Fmax = μ N

Where μ is the coefficient of static motion and N is the normal reaction.

While sliding motion actually occurs, the retarding friction force has the magnitude μk N, where μk is the coefficient of kinetic friction.

The angle among the normal reaction N and the resultant reaction R is called the angle of friction while sliding motion of the surfaces is impending. This angle φ is associated to the coefficient of friction by :

                                                      tan φ = μ

The maximum angle of inclination of the inclined plane, whereas the body kept on it is just on the point of moving down the plane, is called as the angle of repose.

The angle of repose is equal to the angle of friction.

You have also learned in this section, the engineering applications where dry friction plays vital role, e.g. wedges utilized to lift heavy loads and screw jacks frequently used in presses and other mechanisms. By drawing free body diagrams mentioning correct sense of friction forces and applying equations of equilibrium, you may analyse the engineering applications where dry friction is involved. In case of belt and rope drivers, onto a curved surface, whereas sliding motion is impending the ratio of tensions is given by following:

                                           T1 / T2 = eμ α

Where   T1 = tension of the tight side,

              T2 = tension on the slack side,

              μ = coefficient of friction, and

              α = angle of lap in radians.

In case of V belt the above formula is changed by multiplying α by cosec the angle among two surfaces of contact forming V.

Posted Date: 1/28/2013 5:32:43 AM | Location : United States







Related Discussions:- Friction, Assignment Help, Ask Question on Friction, Get Answer, Expert's Help, Friction Discussions

Write discussion on Friction
Your posts are moderated
Related Questions
Explain the autoignition and detonation theory of detonation. What do you mean by preignition ? Describe octane Rating of a fuel. What are the different S.I. engine combustion cham

i would like to know how much it would cost to for my assignment without the actual graphs but the dimentions and without the assignment being converted into a word document as lon

Thrust diagrams for the beam: Illustrate the shear force, bending moment & thrust diagrams for the beam illustrated in Figure Figure Solution Vertical compo


What is fluid mechanics? what are cohesive and adhesive forces?

A  truss  is  shown  in  the  given figure. Compute  the horizontal deflection of  joint D formed by  both  the  load  and  fabrication  error  (bar  AE  is  30mm  too  long).  For

Isentropic flow through the nozzle: In an isentropic flow through the nozzle, air flows at rate of 600Kg/hr. At inlet to the nozzle, the pressure is 2Mpa and temperature is 1

ADVANTAGES OF GAS TUNGSTEN ARC WELDING (GTAW) Produces high quality, low distortion welds Free from spatter The process can be used with or without filler wire This

Determine in brief about the Residual soils Residual soils are generally very complex and varied. They are the products of in-situ disintegration of rocks and weathering. The g

Design of a Bicycle Frame : Figure  depicts a simple bicycle frame, which is to be built of hollow aluminium tubing with outside diameter of 20 mm and wall thickness of 2 mm. The f