×
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

Hertzian stress or?

Hertzian stress or?

Hertzian stress or?

(OP)
LS,

To clamp a measuring device onto a round steel structure, the choice was made to used a kind of "knife". Since the contact area is very small, it is possible to exceed the yield stress of the metal (knife and structure are made from identical materials) and obtain a very stable contactpoint.
Initially we used the formulas for Hertzian stress to calculate the stresses. But the radius of the "knife" blade is difficult to determine and has a large impact on the result. Also plastic deformation will occur, and the contact surface will not be a linecontact anymore.

Does anyone have a suggestion how to solve this?

Thanks,
DYV

RE: Hertzian stress or?

if you want to attach a flat thing to a round thing, and not have either of them to deform (adapting to the other), then you need an adaptor.

this could be a solid piece, like a machined piece profiled to suit both parts, or it could be a formable piece, like epoxy shim.

RE: Hertzian stress or?

(OP)
To have the best possible and stable mounting, we are aiming for plastic deformation. Which means that local stresses should be high enough to exceed the yield stress. The problem is how to calculate, as we have a short line contact in axial direction.

RE: Hertzian stress or?

Do you have Roark? My 6th Ed has a good discussion on Hertzian stresses, their limitations (infinite lengths, types of stress obtained, etc), safe working stresses, knife edge contact, etc.

Do you have access to non-linear FEA code? Might this be required?

Can't quite picture what it is you are trying to achieve, but "a radius that is difficult to determine" that has "a large impact on the result" would seem to be an intractable problem. Is it simply the case that it is difficult for you to determine, and that you could get accurate measurements done somewhere else?

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