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Community Tip - Learn all about the Community Ranking System, a fun gamification element of the PTC Community. X

Press fit check box

346gnu
12-Amethyst

Press fit check box

Hi,

The highlighted check box in the attached image is ticked by default with the default value of ignore interpenetrations larger than 0mm

This means that all contacts will be ignored by default.

For a model with no interpenetrations, the check box either has to be unchecked or the value of 0 increased to encompass all contacts. (anything greater than zero).

So, either the logic should be one of the following:

1. The default state is UNchecked thus defaulting to a pre-creo behaviour

2. The check box should be on by default and the condition should be for interpenetrations LARGER THAN OR EQUAL to 0.

The latter would mean that interpenetrating surfaces would be ignored; not quite pre-creo behaviour.

I favour 1. otherwise there must be check model/diagnostics message stating that the following contacts will be/are ignored unless something is done.

Otherwise this is just another check box I have to remember to uncheck every time I create a contact analysis with no interpenetrations.

Model failures where contacts are definitely there butcould also be a bit cryptic for less experienced users.

Have I misunderstood this or not appreciated the additional flexibility this offers by default?

Any thoughts.

Regards


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1 REPLY 1

I believe that the "for press fit, ignore interpenetrations larger than:" is only for geometry that is initial interference. If the geometry is not in interference/has a gap, then this feature ignored. I ran four test cases to confirm this:

  1. 1/4-symmetry pin and plate w/ hole with an initial interference of 0.05 in and "ignore interpenetrations larger than:" set to 0 in.
  2. 1/4-symmetry pin and plate w/ hole with an initial interference of 0.05 in and "ignore interpenetrations larger than:" set to 0.049 in.
  3. 1/4-symmetry pin and plate w/ hole with an initial interference of 0.05 in and "ignore interpenetrations larger than:" set to 0.05 in.
  4. 1/4-symmetry pin and plate w/ hole with an initial gap of 0.05 in and "ignore interpenetrations larger than:" set to 0 in. A thermal load was applied to the plate to shrink in onto the pin.

The results I got were:

  1. Interpenetration remained; no contact stresses developed.
  2. Interpenetration remained; no contact stresses developed.
  3. Interpenetration removed; contact stresses developed.
  4. Gap removed; contact stresses developed.

Were you having analyses fail if you didn't modify the interpenetration value or uncheck the box?

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