# 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)??
snipped-for-privacy@rediffmail.com wrote in news: snipped-for-privacy@j33g2000cwa.googlegroups.com:
No
If you don't mind can you reason out why?
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

#### Site Timeline

• I'm three years into my mechanical engineering degree at oregon state university...
• next in

## ⚙ Mechanical Engineering

• Hello all, I am looking for information about the Duplex ESSO test. It is a...
• previous in

## ⚙ Mechanical Engineering

• Does anyone know how to locate the CFM rating of Maytag Dryer model MED8630HW?...
• last updated in

## ⚙ Mechanical Engineering

• Does anyone know how to locate the CFM rating of Maytag Dryer model MED8630HW?...
• last posted in

## ⚙ Mechanical Engineering

• Hi, jetzt muss ich auch mal nachfassen: Wer fängt mit einer Diode mit der...
• site's last updated in

## ⏚ Electrical Engineering (German)

• Grawitacja pomaga wytwarzać światło, a to tylko początek niezwykłych...
• site's newest in

## Engineering Science (Polish)

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.