How can I calculate a radial force of a stent pushed in by rigid flat bodies?

Member
edited August 19

Hello,

I am trying to simulate the crimping of a Nitinol stent using Static Structural. I have stent ring in the center and planes placed around it. Over the "Remote Displacement" option are they moving towards the center and by this pushing the stent together. I am using the probe "Force Reaction" selecting the Remote Displacement to calculate the radial force created by the stent.

Is that the right way to get the radial force or is ther maybe another one? I have compared my calculated results to experimentally generated data and the force is much too small. Is there an obvious mistake I have made here or something I could try?

I am glad for any suggestions.

• Member

Please insert images of your stent and the surfaces that are crimping it.

• Member
edited August 20

Hello, here are a general view and in a crimped position from above. The rigid surfaces are meshed with a face sizing (element size 0,5 mm) and the stent with the tetrahedron method. I have also used symmetry to make my model smaller but also want to solve the whole thing to validate using symmetry.

• Member
edited August 21

Remote Displacements moving the surfaces to the center is one way to do it.

Another way is to create a cylindrical surface, and have a cylindrical coordinate system on the stent central axis. Then you can apply a Nodal Displacement on all the nodes on the cylinder to move in a radial direction (X direction in the cylindrical system) and hold Y and Z at 0.

The contact force reported by the contact elements can tell you the total radial force.

If you use Frictional Contact, you might not need any constraints on the stent.

If you use Frictionless Contact, pick three vertices around one end of the stent, approx. 120 degrees apart, and using the cylindrical coordinate system, add a Displacement holding Y and Z fixed at 0 while leaving X free.

• Member

Thank you for these tips. So if I add the Contact Forces of all involved objects (whether there are multiple planes or one cylindrical one) I get the radial force, right?

• Member
edited August 23

Please read the ANSYS help system. Maybe if you have 12 contact pairs, you can get 12 components of total force written to the .CND file. I don't know, I've never tried it. If you have one cylindrical surface, I expect the total force will be zero. However, you could slice the cylindrical surface up into 12 strips to get 12 contact pairs.

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