Question

a. State the difference between personal frequency and excitation frequency
b. State the difference in angular frequency and linear frequency
c. State the difference between transient response and steady state response
d. Mention the different meanings of eigenvalue and eigenvector in the vibration equation
e. Mention the difference between viscous and silencer d

Answer 1

a) Personal frequency : Every body/System will have its own frequency depending on its own parameters like mass, stiffness, etc.. if disturbed and left, the body/system will oscillate with this frequency. It is called personal frequency.

Excitation frequency : The system/body that is originally at rest is excited with an external agent. This could be intentional or unintentional..like a vehicle (spring mass damper) being excited for a speed braker. Sometimes, these excitations will be periodic. The frequency of this external agent is called excitation frequency.

b) Angular Frequency : Angular Frequency is the rate of change of angle per unit time. It is analogous to velocity in linear motion. Its units are rad/sec

Linear Frequency : lf a wave is passing through a point in given space and if we are observing it, the number of times, a particular point of wave (like a crest or trough) passes the point we are observing in 1 second is called linear Frequency. It is the number of unit changes completed per unit of time. It is measured in Hertz.

C) Transient Response : The response of a system to any excitation when t is very small i.e, immediately after the excitation is called steady state response.

Steady State Response : The response of a system to any excitation when t is verly large (theoretically t tending to infinity) is called steady state response.

D) Eigen values and Eigen Vectors : We generally use eigen values and vectors to solve multiple degrees of freedom problems in Vibrational Analysis. In Vibrational Analysis, Eigen values gives us the frequencies of vibration and Eigen vectors are the mode shapes of vibration.

E) Viscous Dampers And Silencers : Both of them are made to reduce the vibrations. A Viscous damper usually consists of a Viscous fluid which opposes the motion of anything that moves through it. When vibrated, a part of the system is made to move through this viscous fluid therby opposing the motion. A silencer on the other hand resuces vibrations to reduce the accoustic noise. When the sound waves are destructively interfered, the sound waves die off thereby reducing the noise.