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
Find speed of dynamo shaft: Q: W ith the help of belt an engine running at 200rpm drives line shaft. The Diameter of the pulley on engine is 80cm and the diameter of the pul

#question. Select a standard rolled steel I-section for the simply supported beam shown in figure below. Select an appropriate factor of safety and material strength. Include ref


I have been tasked to design a web based automatic feature recognition system for a press brake bending machine, how do I go about It?

Q. Intermodular Piping Connections Alignment of pies shall be achieved as detailed in the construction drawings. Special attention shall be paid to the alignment and installati

If Excessive Pedal Pressure Required Causes of Problem Remedy Incorrect shoe placement Improper anchor pin position l


we can use in proove of energy is a propertyof system we can use (E) instead of (dQ-dW)

Explain the working of Michelson's interferometer. How circular fringes he produced with it. (a) What are antireflection films and interference filters? (b) Find the reflecti

The tank can be modelled from first principles with the provision of certain assumptions. For the sake of simplicity, it is possible to consider the top section of the tank with p