Dhristi JEE 2022-24

What is Damping Force?

Damping force definition in physics is involved when vibrating motion is restrained, for example, alternating electric currents, noise, mechanical oscillations, by the energy being dissipated. It is an influence upon or in a system that is oscillating that results in the prevention or reduction of the motion of oscillation. When we talk about physical systems, this is a phenomenon that is a result of processes that end up dissipating energy. For example, a child moving to and fro in a swing – the motion will die down due to damping if the child stops pushing the swing in either direction. 


On the other hand, there can be systems so damped that there is no vibration at all. Critical damping is something that stops vibration or is just enough so that the object can return to the rest position as soon as possible. One example of this is the automobile shock absorber. Additional damping can result in overdamping, and this is necessary in some cases, like in door closers. For undamped systems, the vibrations eventually taper off to being nothing.


Some of the damping examples are carpet pads, vibrating springs, shock absorbers in automobiles, sounds produced by tuning forks over long distances, clock pendulum, oscillations of the branch of a tree, RLC circuits, etc. Friction affects damping as the relative motion between two surfaces pushing against each other to cause dissipation of energy. The kinetic energy in damping gets converted to heat by friction.


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Electromagnetic Damping

Electromagnetic damping is one of the damping techniques that is interesting and uses currents that are induced electromagnetically to be able to slow the motion of a moving object down without there being any physical contact with the object that is moving.


To understand this particular phenomenon, we need to understand eddy currents and electromagnetic induction. The latter is a phenomenon where an electromotive force gets induced in a conductor, and this is something that takes place when there is a change in the magnetic field. This is induced when the conductor gets placed in a changing magnetic field or when it moves across a steady magnetic field.


Damped Vibration

Vibrations are said to be damped when friction and other resistances result in the energy of a vibrating system being dissipated. The vibrations reduce or change in intensity or frequency gradually or even cease, and this results in the system resting in equilibrium. 


If there is a restoring force, the vibratory motion of any system will continue indefinitely if there is no resistance force. Friction will reduce the mechanical energy of this system, and this is what is referred to as damped vibration. The damping will then reduce the amplitude of the vibrations progressively.

 

One example of this sort of vibration is the suspension on vehicles that is dampened by the shock absorbers that are put in place.

Damping also includes the study of the natural frequency of damped vibration and undamped vibration. 


Types of Damping

Even when studying damping, it is important to understand that there are a few main types of damping and how they differ from each other.

  • Light Damping

Here, there is observation of defined oscillations, but their amplitude is reduced slowly over time.


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  • Critical Damping

Here the system will go back to the position of equilibrium as soon as possible with no oscillations at all.


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  • Heavy Damping

Here as well, the system goes back to the equilibrium position with no oscillation, but this is done very slowly. When the resistive forces are more than of critical damping, what happens is heavy damping. 


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Critical damping is necessary so that you can avoid a significant number of oscillations, and also there being too large a time gap where the system is unable to respond to any disturbances that come up. Electrical meters and balances are instruments that get critically damped so that the pointer without oscillation will move to the correct position oscillating. 

To critically damp the suspension of the vehicle, shock absorbers are used so this way the setting up of the vibration is resisted as this can cause damage or make control difficult. 


Importance of Damping

Damping is what is used to limit vibrations, and this is important to protect the system where it is being used. This is something that happens with drawer or door springs, as damping makes sure that blows are prevented when they are opened and closed. On a much larger scale, the same purpose is served by bridge deck damping systems.

 

If there is a dynamic sinusoidal load that is impacting a building structure, in theory, the movements would increase, and the structure would slowly fall down. This is why damping is extremely important to preserve and prevent damage, no matter if it is being used for a small household object like a door spring or even for something much larger as mentioned.

FAQs on Damping Force

1. What is damping?

Damping in physics has to do with when vibrating motion is restrained, for example, alternating electric currents, noise, mechanical oscillations by the energy being dissipated. It refers to the slowing down of motion without any physical contact with the moving object.  

2. Why is damping used?

Damping is used to limit vibrations, and this is important to protect the system where it is being used. This is something that happens with drawer or door springs, as damping makes sure that blows are prevented when they are opened and closed. On a much larger scale, the same purpose is served by bridge deck damping systems. Basically, damping systems preserve and prevent damage to structures, big or small. Some of the damping examples are carpet pads, shock absorbers in automobiles, and such. All these are protective measures that are taken to ensure safety and to prevent as much damage as can possibly be prevented in the case of any mishap.

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