Contact analysis...

[PAULKORENKIEWIC]

Guru's,

We are trying to perform a contact analysis on a "cartridge poppet
valve" assembly, as shown below. The body/seat (tan part) is
non-symmetric which makes the seat under the valve vary in stiffness.
The poppet shaft (green) is also supported by an integral guide in the
body which doesn't show in the picture below. Can anyone point me at
some good information or examples of the use of contacts? Or does
anyone have any advise in dealing with contacts? We are running this in
"steps"... the first was to run everything just "bonded", and the next
is to put contact in at the valve seat, the final is to add the guide
contact. I tried searching ptc.com and looking in the Help CD topic on
Mechanica but really didn't find much of any use.



thanks in advance...

Paul Korenkiewicz
FEV , Inc.
4554 Glenmeade
Auburn Hills, MI, 48326-1766


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[Chris3]

Contact regions are used when you have a free interface between two
parts and a load is being applied. In order to calculate contact
stresses, Mechanica puts springs in between the two surfaces for which
you have defined a contact region. It calculates displacements and if
the surfaces go through each other, it makes the springs stiffer and
then runs the calculation again. It also makes the local mesh in this
region finer.

Because it does these iterative calculations, contact analyses will take
a lot longer than a bonded connection. If you have surfaces that are
bonded together and which will not separate than stick to a bonded
interface.

Chris