Learning Forum

[Natalie Berreth]

I model the quarter model of a ring resting on a round bearing. The load on the ring is applied by a bearing displacement. No matter how I solve the modeling, the error occurs in the enlarged view that the ring detaches from the support. However, if I output the gap, Mechanical indicates that it has negative values and that there is therefore an overlap. Is this just a display problem or have I modeled something incorrectly?
Attached is a picture of the detachment of the deformed ring.

[peteroznewman]

Hello Natalie,

You assume that gaps are reported with postive numbers, but if you read the documentation, gaps are reported with negative numbers.

/forum/forums/topic/contact-tool-solution-gap-vs-penetration/

If you expected the ring to have no gap, change the boundary conditions to something that better represents reality.

[Armin Abedini]

Hi Natalie,

Could you describe what boundary conditions were used for the model? It appears from the picture that quarter-symmetry assumption is violated after deformation.
Also, how did you consider the interactions between the ring and the bearing?

[Natalie Berreth]

Hi Armin,

In the picture above left, the outer ring is held against displacement in a horizontal direction. At the bottom right, the ring is held by a clamp. The bearing is held against rotation in all directions and against horizontal displacement as well as displacement in the plane. 
I have taken the interaction between the ring and the bearing into account by means of a contact surface with friction.

[Armin Abedini]

Thanks Natalie.

From the description, it looks like to me that loading is applied by moving the bearing in the vertical direction. If you're taking advantage of symmetry of the structure, I would suggest that you utilize symmetry regions (like the picture below) instead of manually imposing displacement BCs to represent the symmetry: