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!

*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.

Jobs

STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE
3

STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

i doubt there's a solution for such a specific geometry. You might have more luck if you consider just the OD of the CSK as a "bump" on the hole contour. A conservative model would be to consider the large cut-out but use the CSK as the corner radius.

another day in paradise, or is paradise one day closer ?

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

Obviously this is an upper skin plank; primary structure related to an access hole cut-out. This is no simple fix! If you have the loads - then you have to calculate the critical crack length; and set up a threshold / repeat inspection. Only if the intervals are less than OEM specified detailed wing inspections intervals for that location; will allow removal of this additional special inspection. Never the less - in either case, the inspection interval has to be worked out and submitted to the authorities (Damage Tolerant analysis - DER approval).
- If you do not have the loads or cyclic loading - than this is a good time to get acquainted with the OEM.
- For an added margin of safety - the blended location will have to be NDT crack checked; roto-peened & corrosion-resistance treated.
* Wing plank damage around cut-outs is regarded as significant damage - regardless how small the defect.

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

Peterson's text on stress concentration factors was, and still is, the bible for stress engineers. There
is a 3rd edition that I don't have since being retired for quite some time.
R. Roark's "Formulas for Stress and Strain" has some tables for concentration factors... not very complete.
G-pa Dave pipe

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

(OP)
Thanks, guys.

The blend is at a systems penetration in a wing rib. To design, fatigue life is very high. Treating the blend as a chamfer around the entire circumference and calculating an effective plain hole diameter leads to a stress increase at the attachment holes - no problem. I am left however, with what to do at the blend. edmeister's reply indicates that it is not trivial.

StressMan

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

I remember the example for stress concentration superposition.
Considering the following case: 1) A hole in a plate 2) A notch at the edge of the hole
Stress concentration for each calculated separately.
1) Hole - Kt of 3
2) Notch - Kt of 2
Stress concentration superposition (assuming the notch is located at peak kt location of the hole - normal to loading direction)
Total kt = Hole kt x notch kt = 3 x 2 = 6 (Stress raises too much!)
For this case, chamfer can be assumed as notch, since chamfer is extended to the most of the thickness.

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

it's hard (for me) to see that much of the problem from the pic posted. It looks like it's protruding from a larger cut-out. If it's in the corner of this larger cut-out, that's going to be a problem. If there's a lot of shear, travelling around the larger cut-out, that's going to be a problem.

You might get somewhere if you consider the problem similar to a hole with a bump, and assume the Kt increases by the same ratio ... Kt = Kt_cut-out*Kt_circle_with_bump/Kt_circle

another day in paradise, or is paradise one day closer ?

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

2
The URL below is to a paper that I found a few years ago and thought it may be useful in the MRB / Liaison role. Seems very relevant to your discrepancy.

http://espace.library.uq.edu.au/view/UQ:131820/A1....

Regards

RE: STRESS CONCENTRATION FACTOR, SHORT CHAMFER IN EDGE OF CIRCULAR APERTURE

(OP)
Special thanks to MNLiaison. The linked paper certainly looks pertinent to my case. Thorough study will tell.

Regards,
StressMan

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close