Criteria For Finding Damping Phenomenon:

There are many methods are there for the finding the damping in the system. There are various methods to measures the damping and consistent with the each other, always care must be taken while evaluating damping treatments.

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Single Degree-of-freedom System: In a  free vibration system under an  undamped SDOF system  will never die out and a simple and easiest  approach is to introduce a dissipation will takes place in viscous dashpot system

Usually the damping force(Fd) which is directly proportional to instantaneous velocity

                                                                                                                                                                                      1.1

Where c is called a dashpot or viscous damping constant.

The loss factor(?):Which measures damping phenomenon and defined as the sinusoidal excitation of a system to the corresponding sinusoidal response of the system

                                                                                                                                                                                     1.2

Where k= stiffness of the system.

the above equation is similar to the equation for the viscoelastic systems developed by the Ungar and Kerwin’s in the year 19627

From the above equation 1.2 shows us a linear dependence between loss factor to driving frequency and inversely proportional to the stiffness of the system and this kind of frequency dependence discussed by the Crandall in the year 19708but in actual practices it is not possible this form and in such a case often resorts to an equivalent ideal dashpot system. The theoretical objections to the approximately  constant value of damping over a range of frequency, as  observed in aero elasticity problems have been raised by the Naylor in the year 19709.From the equation1.2 frequency- dependent dashpot system is given by the

                                                                                                                                                                          1.3

The above equation shows a physical limitations, In the year 1970,1991 Crandall8 in 1989 Newland10 and in 1970 Scanlan6 have found that representation volatile’s causality.