Learning Forum

[fabio1997]

Hello everybody, I need help with a double ball bearing without rotation speed . I'm working with frictionless contact .I'm looking for stress on the ball contact. This is what i've done.

Mesh : face sizing on the spheres (8) and on the trail (8)

Contact :Frictionless. Behavior :Asymmetric . Formulation :augmented lagrange.

Cyclic symmetry with 36 sectors. Large delfection ON.

Force on the lower surface of the internal ring. Fixed support on the upper surface of the external ring. Displacement boundary conditions with cilindrical orientation to prevent ball slidings and trail circumferential slidings.

I've put 4 contact regions (upper balls and lower balls with external and internal ring)

Immagin2.png

[Gary_S]

It seems something is not correct with the contact definitions. You can use an Initial Contact Tool in the Connections branch, and also Contact Tool in Solution branch.
We have several videos posted on how to use. On YouTube, search "ansys contact tool"

[fabio1997]

Thank for your answer this is what i see in the initial contact.

[mrife]

The initial contact information shows that all the contact pairs are initially open however each has a different gap size. So it looks like one contact pair (or maybe more, hard to tell from the limited number of pictures) got closed and is taking the whole load. I take it you intend for all the bearing balls to be in an initial touching state?
Mike

[fabio1997]

Hi Mike, thank you for your answer.
In SpaceClaim i've drawn sphere (contact) and trail (target) with the same diameters ( 44mm ) so the gap come with the mesh.
The contact closed is maybe about the Asymmetric Behaviour ,i put Adjust to Touch in the Interface tretment to see the stress in the lower balls. But now i have this issue in modal .
I've got Hertz=0 but the red sphere is moving vertically for no reason...

[peteroznewman]

The red balls in the Modal analysis float around because the initial contact status was Near Open and not Closed.
Modal analysis cannot use Frictionless Contact because that is nonlinear, while modal is a linear analysis.
Frictionless contact that is closed is automatically converted to Bonded contact in a Modal analysis.
Frictionless contact this is near open is automatically suppressed in a Modal analysis.