Odd bolted joint behavior...

[PAULKORENKIEWIC]

Guru's,

I have a bolted joint as part of an analysis that I've applied advanced
fastener features to. I have the fasteners defined as a bolt with
pretension and the fix rotation and carries shear boxes checked. The
fastener results look like this:
This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.

[lylebeidler]

Paul,

One thing you should do is find what the displacement you're seeing actually
is - ie, be SURE it's not a scaling thing in the results view. I'd do this
by plotting the displacement, instead of stress, in the direction normal to
a plane that holds both of those axes.



--



Lyle Beidler
MGS Inc
178 Muddy Creek Church Rd
Denver PA 17517
717-336-7528
Fax 717-336-0514
<">mailto:-> -
<">http://www.mgsincorporated.com>

[PAULKORENKIEWIC]

Yeup, considered that, but for the record here is the picture of those
results:


Thanks...

Paul Korenkiewicz
FEV, Inc.
4554 Glenmeade
Auburn Hills, MI., 48326

[JonathanHodgson]

Do the bolt elements have either a clearance or a stiffness?

From both the stress and displacement plots, some shear load is
definitely being transferred at the contact surface/edge, and given that
your displacement plot is nearly 100:1 it's only a small displacement
(0.32 mm, I assume, unless this part is /huuuuge/ - what is your full
units system? mm and N?)

I'm inferring that the part on the right has the applied loads
(upwards), and the part on the left is restraining it.

Presumably the shear load of 33729 'forces' is greater than the contact
friction in the bolted face...

Jonathan

[PAULKORENKIEWIC]

Yes... interesting point... I just was expecting the holes to stay
more in alignment, especially at the face. Looking at the deflection
at that face, parallel to it, the one part is maxing out at 0.1 and the
other at 0.32... I am going to crank up the pretension on the
fasteners. My thought is that this will reduce this difference.

Thanks...

Paul Korenkiewicz
FEV, Inc.
4554 Glenmeade
Auburn Hills, MI., 48326

[PAULKORENKIEWIC]

I'm using the fastener function in Mechanica. I don't think it deals
with clearance, and the stiffness is calculated based on material and
diameter... in this case 15mm and steel.

I am definitely thinking, after all you help, that it IS just a matter
of scale... see my earlier posts...

Interesting comment here about the shear load and friction. If I
calculate the required coefficient of static friction required for the
friction force developed by the tensile load to balance the shear load
it comes out to 0.419. Both parts are 80-55-06 cast iron and this
assembly is living in a cavity of automatic transmission fluid. I
wouldn't think the coefficient would be that high for these. Of course,
the fastener function doesn't have any "friction" adjustability... at
least as far as I know. Or does it???

Thanks...

Paul Korenkiewicz
FEV, Inc.
4554 Glenmeade
Auburn Hills, MI., 48326