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rajbeermalhotra@rediffmai
science forum beginner
Joined: 19 May 2006
Posts: 2
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 Posted: Fri May 19, 2006 5:26 pm Post subject:
Question on Structural Dynamics
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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!!) |
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Greg Locock
science forum Guru Wannabe
Joined: 28 May 2005
Posts: 111
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| Posted: Sat May 20, 2006 9:54 am Post subject:
Re: Question on Structural Dynamics
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rajbeermalhotra@rediffmail.com wrote in
news:1148059566.384864.315950@j33g2000cwa.googlegroups.com:
| Quote: | 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)??
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No |
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rajbeermalhotra@rediffmai
science forum beginner
Joined: 19 May 2006
Posts: 2
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| Posted: Sat May 20, 2006 11:29 am Post subject:
Re: Question on Structural Dynamics
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If you don't mind can you reason out why? |
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Greg Locock
science forum Guru Wannabe
Joined: 28 May 2005
Posts: 111
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| Posted: Sat May 20, 2006 10:59 pm Post subject:
Re: Question on Structural Dynamics
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rajbeermalhotra@rediffmail.com wrote in news:1148124567.903689.103370
@i39g2000cwa.googlegroups.com:
| Quote: | If you don't mind can you reason out why?
|
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 |
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