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
Q. Design the drainage area? Areas beneath equipment or vessels subject to spills or leaks shall have slope drainage area. Every skid shall be provided with floor drains. S

The suspension system of a car is modelled as having an effective stiffness of 5x10 6 (N/m) and an effective mass of 750 (kg). The car is travelling over a road with bumps that ca

Find out the safe power transmitted by pulley: A belt drives pulley of 200mm diameter such that ratio of tensions in tight side and slack side is 1.2. If maximum tension in b

what is mean by minimum work term in reciprocating compressor?

Types of Cooling System: Two types of cooling system are used in two wheelers. (a) Natural air-cooling. (b) Forced air-cooling.

Explain the Bar and Rod Drawing - cold drawing processes In case of bar drawing, hot drawn bars are at first pickled, washed and coated to prevent oxidation. Once it's done

Find out the centroid of an area of a semicircle: Find out the centroid of an area of a semicircle illustrated in Figure. Solution You shall note that it is not p

Compressio n Ratio: It is calculated as shown below Mea n Effective Pressure (P m   o r P me f ): Mean effective pressure is the hypothetical consta

A hole of 25 mm diameter and 62.5 mm depth is to be drilled. The suggested feed is 1.25 mm/rev.and the cutting speed is 60 m/min. Assume the clearance height is 5 mm. Determine: f

Material Selection and Process Mapping Selecting an optimal material from numerous candidates in one competitive aspect of manufacturing depends on factors such as properties,