Question on Structural Dynamics

Question on Structural Dynamics
I have been reading Structural Dynamics by Anil K. Chopra and am
currently on the topic "Response of a Single Degree of Freedom System
to Harmonic Excitation.
Can anyone help me with following clarifications??
1. Consider the Displacement Response Factor:
It is the ratio of dynamic deformation amplitude to static
deformation amplitude. Now, when the ratio of the forcing frequency to
the natural frequency of the system (Single Degree of Freedom System)
is less than one (indicating a gradually varying force) then this
displacement response factor is only slightly greater than one
indicating that the contribution due to dynamic effects is negligible.
Right?
Then when the ratio of the forcing frequency to the natural frequency
of the system (Single Degree of Freedom System) is very much greater
than one (indicating a rapidly varying force) then this displacement
response factor approaches zero. Again there is no contribution due to
dynamic effect.
Only when the ratio of the forcing frequency to the natural frequency
of the system (Single Degree of Freedom System) approaches one
(approaching resonance) the dynamic effect becomes dominant and damping
plays a significant role? Right?
Does this mean one should worry about the dynamic response (as far as
dynamic deformation is concerned) only in case of resonance
(considering harmonic excitation)??
Please help (the question though may be stupid!!)
Reply to
rajbeermalhotra
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snipped-for-privacy@rediffmail.com wrote in news:1148124567.903689.103370 @i39g2000cwa.googlegroups.com:
Because in practice the response away from resonance is important in many real world systems.
In some systems the excitation is very strong at a frequency that is nowhere near resonance, in other systems the general damping is high, so the off resonant response is a significant fraction of the resonant response.
Finally, if we attach a system that is excited at resonance, to another that is not, we will generate high stresses in the non-resonant structure.
Cheers
Greg Locock
Reply to
Greg Locock

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