×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Structure Cracks due to Vibration/Resonance and Fatigue

Structure Cracks due to Vibration/Resonance and Fatigue

Structure Cracks due to Vibration/Resonance and Fatigue

(OP)
Dears,
When a structure fails, got cracks after a certain number of hours in the field, one possibility is fatigue failure, other is vibration related, there might be resonance occurring. How the failure due to resonance/vibration is quantified. What is the analytical way of relating the frequencies, resonance to the number of hours to failure? Which failure, due to resonance or due to fatigue, will be earlier.
In the Response analysis of the structure, how the test data of vibration be used, and in what format the test date should be, to use for Response analysis.

Thanks a lot for the input/referring to literature/books.

RE: Structure Cracks due to Vibration/Resonance and Fatigue

The wiseacre in me would tell you to give the problem to someone who knows what they are doing. However, I am feeling kind of nice today and I will give you some hints: Fatigue failures will occur at stresses that can be well below material yield. If you are indeed experiencing resonant conditions it is possible that the stresses due to resonance could exceed yield or ultimate strength.

Also, try "Shock and Vibration Handbook" ISBN 0-07-137081-1

RE: Structure Cracks due to Vibration/Resonance and Fatigue

Ressonance will occur when the loading frequency is near one of the component natural frequencies (mainly close to the 1st natural frequencies).

Fatigue will occur in all problems that have cyclic loading and the higher component stress is above the Fatigue Limit. Obviously, the component stresses during ressonance will be higher and it will failure by fatigue before, then compared to a situation of non-ressonance.

I reccomend you to read about fatigue (for example the chapter 6 of the Shigley's Mechanical Engineering Design; it is a very very simple text on fatigue, just to introduce the readers to the subject) and also a book on vibration (I find good the book "Mechanical Vibrations" by "Singiresu S. Rao").

Regards,

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources