www.www.buonovino.com

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

Forum SubscriptionsSubscriptionsDigestDigest PreferencesFAQFAQSearchSearchMemberlistMemberlistUsergroupsUsergroupsRegisterRegisterFAQ安全提示FAQDonate
ProfileProfileLog in to check your private messagesLog in to check your private messagesLog in to websiteLog in to websiteLog in to websiteLog in to forum
Warning: Make sure you scan the downloaded attachment with updated antivirus tools before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

Effect of Damping on Steady State Vibration:Harmonic Excitat

This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies. www.www.buonovino.com Forum Index->Past Discussions Year 2006
View previous topic::View next topic
Author Message
rajbeermalhotra
SEFI Regulars
SEFI Regulars


Joined: 26 Jan 2003
Posts: 20

PostPosted: Mon Nov 27, 2006 11:56 amPost subject: Effect of Damping on Steady State Vibration:Harmonic Excitat Reply with quote


Considering the response of a single degree of freedom system to harmonic excitation with viscous damping , following conclusions can be drawn:

Now,

The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

But, it is also observed that the amplitude of the steady state response incraeses with time.This can be mathematically be proved easily as a consequence of the solution of the differential equation.

My question is:

1)What is the physical reasoning for the amplitude of the steady state response increasing with time?

Besides,
It is also found that the amplitude of the steady stae response is more in systems without damping (a theoretical case though) and is less in systems with damping.Right?

My question is:

2)That means, damping palys a role in reducing the amplitude of both steady state response as well as transient response?But, the transient (free vibration) response eventually decays completely as a consequence of dapming.Right?
Can anyone throw some more light on this???

Posted via Email
Back to top
View user's profileSend private message
Akshaya.Das
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 16

PostPosted: Mon Nov 27, 2006 12:42 pmPost subject: Effect of Damping on Steady State Vibration:Harmonic Excitat Reply with quote

Dear Mr Rajbeer,

I have understand your question. It will be easier for me to answer your question, if you elaborate the context.

Dr A K Das

-----Original Message-----
Message From rajbeermalhotra[AT]red... [mailto:rajbeermalhotra[AT]red...]
Sent: Monday, November 27, 2006 10:56 PM
To: Das, Akshaya
Subject: Effect of Damping on Steady State Vibration:Harmonic Excitation


Considering the response of a single degree of freedom system to harmonic excitation with viscous damping , following conclusions can be drawn:

Now,

The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

But, it is also observed that the amplitude of the steady state response incraeses with time.This can be mathematically be proved easily as a consequence of the solution of the differential equation.

My question is:

1)What is the physical reasoning for the amplitude of the steady state response increasing with time?

Besides,
It is also found that the amplitude of the steady stae response is more in systems without damping (a theoretical case though) and is less in systems with damping.Right?

My question is:

2)That means, damping palys a role in reducing the amplitude of both steady state response as well as transient response?But, the transient (free vibration) response eventually decays completely as a consequence of dapming.Right?
Can anyone throw some more light on this???

这电子邮件和任何附件是保密的d may be privileged or otherwise protected from disclosure. It is solely intended for the person(s) named above. If you are not the intended recipient, any reading, use, disclosure, copying or distribution of all or parts of this e-mail or associated attachments is strictly prohibited. If you are not an intended recipient, please notify the sender immediately by replying to this message or by telephone and delete this email and any attachments permanently from your system.

Posted via Email
Back to top
View user's profileSend private message
rajbeermalhotra
SEFI Regulars
SEFI Regulars


Joined: 26 Jan 2003
Posts: 20

PostPosted: Mon Nov 27, 2006 3:16 pmPost subject: Effect of Damping on Steady State Vibration:Harmonic Excitat Reply with quote

Thanks or the response.Basically, am reading the book "Dynamics of Structures" by Anil K.Chopra and had the clearifications mentioned.I elaborate below as you required:

1)The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

My questions:

1)It is observed that the amplitude of the steady state response is more in a systen without damping and less in a system with damping.What is the reason for this?

2)Also, it is observed that, if we make a plot between the no. of cycles on the x axis and the amplitude of oscillation on the y axis, it is observed that lighter the damping greate is the number of cycles required to acieve a certain percentage of steady state amplitude.What is the reason for this?

Please help!!



On Mon, 27 Nov 2006 Akshaya.Das[AT]ake... wrote :
Quote:
Dear Mr Rajbeer,

I have understand your question. It will be easier for me to answer your question, if you elaborate the context.

Dr A K Das

-----Original Message-----
Message From rajbeermalhotra[AT]red... [mailto:rajbeermalhotra[AT]red...]
Sent: Monday, November 27, 2006 10:56 PM
To: Das, Akshaya
Subject: Effect of Damping on Steady State Vibration:Harmonic Excitation

Considering the response of a single degree of freedom system to harmonic excitation with viscous damping , following conclusions can be drawn:

Now,

The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

But, it is also observed that the amplitude of the steady state response incraeses with time.This can be mathematically be proved easily as a consequence of the solution of the differential equation.

My question is:

1)What is the physical reasoning for the amplitude of the steady state response increasing with time?

Besides,
It is also found that the amplitude of the steady stae response is more in systems without damping (a theoretical case though) and is less in systems with damping.Right?

My question is:

2)That means, damping palys a role in reducing the amplitude of both steady state response as well as transient response?But, the transient (free vibration) response eventually decays completely as a consequence of dapming.Right?
Can anyone throw some more light on this???

这电子邮件和任何附件是保密的d may be privileged or otherwise protected from disclosure. It is solely intended for the person(s) named above. If you are not the intended recipient, any reading, use, disclosure, copying or distribution of all or parts of this e-mail or associated attachments is strictly prohibited. If you are not an intended recipient, please notify the sender immediately by replying to this message or by telephone and delete this email and any attachments permanently from your system.


Posted via Email
Back to top
View user's profileSend private message
Akshaya.Das
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 16

PostPosted: Tue Nov 28, 2006 7:09 amPost subject: Effect of Damping on Steady State Vibration:Harmonic Excitat Reply with quote

Please find my reply below:

1)

a) In simple words, damping in vibrating structure results resisting force against vibration. It is the reason that the system without damping (which is pactically impossible)having more responses than system with damping. This is not only true for transient state , also for steady state.

b) I would like to mention that tansient vibration is not equivalent to free vibration, as you stated. Transient vibration is a state where vibrating body is accelerating before reaching uniform velocity or steady state.

C) If a system is exited by momentary force and subseqently force is withdrawn, and allow the sytem to vibrate freely without damping, is termed as Free Vibration.

2) Ligthly damped system always take more nos of cycles to achieve steady state amplitude than heavily damped system. Heavy damping reduces the duration of transient vibration and leads to steady state amplitude faster.

I hope I have understand your this question properly.

Regards,

Dr A K Das

-----Original Message-----
Message From rajbeermalhotra[AT]red... [mailto:rajbeermalhotra[AT]red...]
Sent: Tuesday, November 28, 2006 2:16 AM
To: Das, Akshaya
Subject: Effect of Damping on Steady State Vibration:Harmonic Excitation

Thanks or the response.Basically, am reading the book "Dynamics of Structures" by Anil K.Chopra and had the clearifications mentioned.I elaborate below as you required:

1)The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

My questions:

1)It is observed that the amplitude of the steady state response is more in a systen without damping and less in a system with damping.What is the reason for this?

2)Also, it is observed that, if we make a plot between the no. of cycles on the x axis and the amplitude of oscillation on the y axis, it is observed that lighter the damping greate is the number of cycles required to acieve a certain percentage of steady state amplitude.What is the reason for this?

Please help!!



On Mon, 27 Nov 2006 Akshaya.Das[AT]ake... wrote :
Quote:
Dear Mr Rajbeer,

I have understand your question. It will be easier for me to answer your question, if you elaborate the context.

Dr A K Das

-----Original Message-----
Message From rajbeermalhotra[AT]red...
[mailto: rajbeermalhotra[在]红…]
Sent: Monday, November 27, 2006 10:56 PM
To: Das, Akshaya
Subject: Effect of Damping on Steady State Vibration:Harmonic
Excitation

Considering the response of a single degree of freedom system to harmonic excitation with viscous damping , following conclusions can be drawn:

Now,

The response of a single degree of freedom system to harmonic excitation can be split into:

a) Steady Sate response (or vibration) which is a result of the applied force.
b)Transient vibration which is the the result of the free vibration and is dependent on the initial conditions.Right?

Now, the transient vibration decays with time as a consequence of damping.Right?

But, it is also observed that the amplitude of the steady state response incraeses with time.This can be mathematically be proved easily as a consequence of the solution of the differential equation.

My question is:

1)What is the physical reasoning for the amplitude of the steady state response increasing with time?

Besides,
It is also found that the amplitude of the steady stae response is more in systems without damping (a theoretical case though) and is less in systems with damping.Right?

My question is:

2)That means, damping palys a role in reducing the amplitude of both steady state response as well as transient response?But, the transient (free vibration) response eventually decays completely as a consequence of dapming.Right?
Can anyone throw some more light on this???

Everywhere

这电子邮件和任何附件是保密的d may be privileged or otherwise protected from disclosure. It is solely intended for the person(s) named above. If you are not the intended recipient, any reading, use, disclosure, copying or distribution of all or parts of this e-mail or associated attachments is strictly prohibited. If you are not an intended recipient, please notify the sender immediately by replying to this message or by telephone and delete this email and any attachments permanently from your system.

Everywhere

这电子邮件和任何附件是保密的d may be privileged or otherwise protected from disclosure. It is solely intended for the person(s) named above. If you are not the intended recipient, any reading, use, disclosure, copying or distribution of all or parts of this e-mail or associated attachments is strictly prohibited. If you are not an intended recipient, please notify the sender immediately by replying to this message or by telephone and delete this email and any attachments permanently from your system.

Posted via Email
Back to top
View user's profileSend private message
Display posts from previous:
This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies. www.www.buonovino.com Forum Index->Past Discussions Year 2006 All times are GMT
Page1of1



Jump to:
Youcannotpost new topics in this forum
Youcannotreply to topics in this forum
Youcannotedit your posts in this forum
Youcannotdelete your posts in this forum
Youcannotvote in polls in this forum
Youcanattach files in this forum
Youcandownload files in this forum


© 2003, 2008 SEFINDIA,Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service.advertisement policy
Baidu
map