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 4:20:38 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
Bucket conveyors are used to moves the granular powdered or liquid materials. The buckets may be mounted on a chain or a belt. The movement may be vertical or flat. The ver

1. The linkage system below consists of two bars A & B plus 4 linkages. Each linkage has a square cross section. The allowable tensile strength of all members is 200 MPa, the allow

Q. How can you implement chemically coated sand? Chemically coated sand : Clean silica grains are sometimes coated with a non thermosetting hydrocarbon resin, which acts as a

alternative theorems for lamis theorem

A thin spanwise symmetrical wing has an aspect ratio of 10 and a straight edges with  taper ratio (tip chord / root chord) of 0.8 and root chord of 1 m. This wing does not have geo

The following steps are taken to decarbonise the engine : Remove the exhaust muffler. Disconnect the spark plug. Remove the intake pipe bolt. Loosen the bolt de

Q. What is Transfer molding? Transfer molding was developed largely to avoid the disadvantages found which compression molding. • Transfer molding can make intricate or quit

Reduce expressions for the hydrostatic center and force of pressure in case of an inclined plane surface submerged in a fluid.

Q. Which functions used for coating? • Improves arc stability by providing certain chemical which have this ability, by ionizing the path of arc. • Provides a protective gaseou

Ladder friction: .: A ladder is an arrangement which is used for climbing on the walls. It consists of two long uprights of wood or iron and connected by many cross bars. Th