×
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

Fatigue analyisis

Fatigue analyisis

Fatigue analyisis

(OP)
Hello,

I am trying to conduct a fatigue analysis of two riveted plates with inputted residual stresses. to do this i am applying pressures to the outside area of the rivet to simulate the residual stresses and writing it to an inital LS file. Next i've applied the maximum load and written it to an LS file. Finally the max stress is removed and the minimum stress applied and written to LS file 3. i have then solved these three files and read them all within the Fatigue section.

The alternating stresses i obtain are almost identical to the values i get when no residual stresses are input and the only reason for this i can imagine is an incorrect analysis procedure.
Could anyone please comment on the manner in which i am carrying out this fatiuge analysis and suggest where i might be going wrong.

Thanks
Alan

RE: Fatigue analyisis

The residual stress is a constant on the stress state - fatigue requires an alternating stress state.  Based on that, why would you expect to see a different result?

RE: Fatigue analyisis

(OP)
Thanks for your reply,

I am applying an alternating stress to the end of the specimen by the form of a max and a min pressure. The residual stress needs to remain on the speciment throughout testing so i was applying it in an earlier LS file and leaving it on the file for the other loads.

How would you advise i incorporate this residual stress?

RE: Fatigue analyisis

Read my response above again - WHY do you expect to see a different result, based on the fact that fatigue is driven by ALTERNATING stress?

RE: Fatigue analyisis

(OP)
I acknowledge your point and understand. only the fatigue life  if affected by residual stresses from the cold working of the hole during riveting. These are the forces i am trying to include but cannot find the literature explaining how to incorporate them succesfully.

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