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Subject: Re: [struct] Bolt Stress Concentrations
Author: Marco Perucchi
Date: 2003-04-25 08:26:00

> Just going to keep this as short as possible. I'm currently doing a
very
> simple 2D axisymetric model of a standard bolt in tension. Problem
is, for
> what is a known loading condition which does not produce plasticity
or
> failure (from years of industry experience), the model is showing
massive
> stress concentrations around the 'under head' radius. This is, of
course, to
> be expected, but would classically indicate a potential failure.
The Ansys
> help people have assured me that the model is correct, and that
this type of
> anomaly should be expected and not taken literally, but this
argument is
> quite difficult to take to management!
> I was wondering if anyone else had experienced this problem, and if
there is
> an agreed way of determining failure criteria in this case. By the
way, I've
> only got Ansys 5.5.1, which doesn't have the failure criteria
portion to it.

Geoff

You should elaborate the results a little bit more.
Does the stress concentration remain local? Is the load static or
dynamic?
If there are local stress peaks under static load I see no reason for
a failure of the bolt - if the material is ductile enough. Anyway, a
corrctly designed bolt should experience only low alternating loads.
There are a couple of interesting postings about bolts by Chris
Wright.
And you won't notice plastic deformation if the plastic region is
small. You could check this easily with a simple elastic-plastic
analysis).

Regards,

Marco Perucchi
Delta JS AG
Zurich, Switzerland
Posts possibly associated with message #49579AuthorDateScore
49576[struct] Bolt Stress ConcentrationsCooper, Geoff geoff.cooper@2003/04/25 
49579Re: [struct] Bolt Stress ConcentrationsMarco Perucchi2003/04/25 
49581Re: [struct] Bolt Stress ConcentrationsMark Krueger2003/04/25 
49585Re: [struct] Bolt Stress ConcentrationsJohn Ceko2003/04/25 
49590Re: [struct] Bolt Stress ConcentrationsRonnie Thomas2003/04/25 
49591Re: [struct] Bolt Stress ConcentrationsChristopher Wright1969/12/31 
49592Re: [struct] Bolt Stress ConcentrationsIan Prentice2003/04/25 
49594Re: [struct] Bolt Stress ConcentrationsPhilippe Vidori2003/04/25