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Transient Contact Modeling - Subdomain Separation

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Hi,


Problem: 2D Elastic cylinder resting on top of an 2D elastic plate, a transient force is applied to the bottom of the plate, pulling it down and releasing it (like a drum head). The sides of the plate are fixed. Watch resulting dynamics.

When I model this using a line of symmetry (not axisymmetric) the results look ok, the cylinder will detach from the plate and move off with constant speed, as it should (the cylinder should not undergo tension with the plate only compression).

But, when I model this is in simple 2D, no symmetry, there is always a point of contact between the cylinder and plate, even when the plate contracts back down, it 'pulls' the cylinder with it.

I have contact pairs between the cylinder and plate, and I turned off solving for contact pressure in the solver.


Any Ideas?
Thanks!

Chris

2 Replies Last Post 01.02.2012, 12:55 GMT-5
Nagi Elabbasi Facebook Reality Labs

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Posted: 1 decade ago 01.02.2012, 12:11 GMT-5
The cylinder and the plate probably share a geometry point. If so, you can keep the parts separate either by using “Assembly” instead of “Union” as a final geometry step or making sure there is a small initial gap between the cylinder and plate.

Nagi Elabbasi
Veryst Engineering
The cylinder and the plate probably share a geometry point. If so, you can keep the parts separate either by using “Assembly” instead of “Union” as a final geometry step or making sure there is a small initial gap between the cylinder and plate. Nagi Elabbasi Veryst Engineering

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 01.02.2012, 12:55 GMT-5
Hi

Indeed you should use a contact with a small offset, to allow your mesh to survive in between the parts touching (if you have a material or a mesh in between, that depends on your model)

--
Good luck
Ivar
Hi Indeed you should use a contact with a small offset, to allow your mesh to survive in between the parts touching (if you have a material or a mesh in between, that depends on your model) -- Good luck Ivar

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