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How prevent an object from penetrating another object?

The attached file has a simple case that is a precursor to what I really need to model. The simple case consists of a membrane (hyperelastic material model) with a small quartz bead located a short distance underneath the membrane. A force is applied to the top of the membrane such that it deflects downward toward the bead. The bead is constrained to remain fixed in space. As the membrane deflects to where it hits the bead, I want to see how the membrane deforms around the bead. However, as shown when you click on "3D Plot Group 4", the membrane does not know the bead is there and becomes superimposed on it within the same volume. How do I prevent this from happening such that I can study how the membrane deforms around the bead? Any assistance would be greatly appreciated!


2 Replies Last Post Dec 14, 2012, 2:28 AM EST
Henrik Sönnerlind COMSOL Employee
Posted: 5 years ago Dec 12, 2012, 2:34 AM EST
Hi,

You need to add a Contact Pair under Definitions, and then a Contact feature under Solid Mechanics where you select the contact pair. As the bead is fixed, it must be chosen as "Source" in the contact pair.

Make sure that the shape of the rather small bead is well resolved by the mesh.

Regards,
Henrik
Hi, You need to add a Contact Pair under Definitions, and then a Contact feature under Solid Mechanics where you select the contact pair. As the bead is fixed, it must be chosen as "Source" in the contact pair. Make sure that the shape of the rather small bead is well resolved by the mesh. Regards, Henrik

Posted: 5 years ago Dec 14, 2012, 2:28 AM EST
Thanks, Henrik. I followed your instructions, and also increased the bead size to avoid potential meshing problems. These are included in the attached file. Note, however, that the membrane still doesn't behave correctly in that (as shown in 3D Plot Group 4) the bead comes partially up through the membrane, rather than the membrane deforming around the bead. What am I missing?
Thanks, Henrik. I followed your instructions, and also increased the bead size to avoid potential meshing problems. These are included in the attached file. Note, however, that the membrane still doesn't behave correctly in that (as shown in 3D Plot Group 4) the bead comes partially up through the membrane, rather than the membrane deforming around the bead. What am I missing?

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