×
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

residual stress

residual stress

residual stress

(OP)
hi

i have results from an elastic analysis (using ANSYS)that indicates some regions of a structure go possibly 10ksi above the yield point under a certain load.

is there a sensible way to determine the residual stresses thoughout the structure after this load is removed (some material has yielded).

what i actually need to do is to determined the new unloaded distortion of the structure without doing a plastic analysis.

i am inclined to run the following elastic case..... apply a stress distribution to the structure (the original loads removed) that is shaped like the loaded stress distribution and that takes the yielded region to 10ksi.  this inherently implies that the residual stress in the yielded region is 10 ksi and the surrounding stresses are proportional to the loaded case.

i believe this would be conservative, but would appreciate any comments.

plastic analysis is not an option.

thanks

daveleo



RE: residual stress

daveleo,

One possible solution, and it would be very conservative at that, is to take the FEA strain value and plot this value on the material stress/strain curve.  Then draw a line from this point at the same slope as the Elastic modulus back to the zero stress line.  Read off the corresponding stress at this location.  This is the residual stress in the part.  If you can show this good, then you are laughing.

This tends to be very conservative for small areas of plastic strain surrounded by a large mass of elastic material.  This is because the energy of the elastic material far exceeds that of the plastic zone and forces a return to a near zero displacement.  For example, hole cold working or shotpeening.  In these examples, the springback is large enough to induce compressive residual stresses in the plastically deformed region.

Also, the plastic strain reported by FEA is conservative as you would likely have load redistribution due to yielding.

Regards,

jetmaker

RE: residual stress

(OP)
jetmaker..... we are thinking along similar lines on this. it's not a perfect academic method, but it should put me in the ballpark....if the resulting deflection has lots of safety margin, i can say we are okay.

thanks for the input.

daveleo

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