fussing with fasteners...

[PAULKORENKIEWIC]

I've got a couple of steel framework "boxes" that are bolted together.
They are loaded "cantilever-like", with one box fixed and the other with
a load on top. The "boxes" are bolted together with 6 bolts. I set up
the Mechanica study with the constraints and loads as described. I used
the advanced fastener function, identically, for the six bolts. The
mating holes are aligned identical in size. When ever I try to run a
static solution, I receive the following failure in the report file,
right after it states that 8300 elements were automatically created and
that there were no errors found in the model:

Convergence Loop Log: (12:32:33)

>> Pass 1 <<

The design study terminated abnormally.

An internal engine error has occurred. Please be sure
to run error checking before you run this study. If
you have run error checking, then contact Customer Support.

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[PAULKORENKIEWIC]

The mechanica fasteners will not work through a hollow tube that way.
You would need to create beam elements for the fasteners and define
contact (maybe with friction) between the tubes. Basically a mechanca
fasteners cannot go through more than two thickness of material. Your
going through 4 thickness if you count the two walls of each tube.



---Jim Holst

[PAULKORENKIEWIC]

I thought that was the answer, but then I remember that I successfully
ran the following assembly with an identical fastener reaching thru
TUBES, so ...


Very strange... and confusing...

[iapanovitch]

I've had some success with using Mechanica Fasteners going through more than two thicknesses in the past. Basically, you need to turn off the "separation spring" option (which works in place of Contact between the fastened parts to ensure non-penetration) in the Advanced Fastener, and use Contact instead. To the best of my knowledge, Mechanica Fastener often fails because it has trouble creating that "separation spring" thing.
Also to the best of my knowledge,PTC support hasa whitepaper explaining all that stuff, which is quite handy when troubleshooting failing Fasteners.
-- Iouri (Yuri) Apanovitch

--- On Fri, 6/17/11, Korenkiewicz, Paul <-> wrote: