ABAQUS Dynamic Explicit: Stent Crimping

[suz_02]

Hello,

I am having trouble with crimping a stent using the Dynamic/Explicit Step ( 2 steps in the model: (1) initial and (2) Dynamic/Explicit). It is aborting or stops running completely, without crimping the stent at all.

I am trying to apply an inward, radial displacement (smooth step 0->1) to the centre of 12 rigid plates (reference point at the centre of the plates), that are ordered in a cylindrical manner.
I am using the general contact method with the following interaction properties: Tangential -> Penalty -> Friction Factor =0.1 and Normal -> Hard. I have also used tie contacts between the cylindrical coordinate centre (RP1) and at some point from the geometry (RP2), where RP2 has an encastre BC.

I have used semi-automatic mass-scaling and have applied mass-scaling to poor-mesh-elements using the minimum time increment specified for the free tetrahedral mesh (seed size 0.1 and element type 3D element).

I have set used the point mass/inertia for the rigid plates: mass of the rigid body to be 1 and the rotational inertia (no diagonal terms) to be 1 also. The reference point is at the centre of the rigid body.

I keep getting the following warnings:

(1) TYPE=BELOW MIN mass scaling will be ignored for mass elements.
(2) TYPE=BELOW MIN mass scaling will be ignored for Rotational elements.
(3) OP=NEW on *CONTACT is ignored when the general contact definition is specified as model data.
(4) The option *boundary type = displacement has been used; check status file between steps for warnings on any jumps prescribed across the steps in displacement values of translational dof. For rotational dof make sure that there are no such jumps. All jumps in displacements across steps are ignored

Any solutions to these warnings would be greatly appreciated!

 

[FEA way]

I keep getting the following errors:

Those are all warnings, not errors so they don't prevent the analysis from running. Aren't there any actual error messages when it fails ?

 

[suz_02]

sorry I meant to write warnings, I did not get any errors however, I ran this for 4 days and it was stuck at one time step and not continuing.

These warnings kept appearing every time I ran the simulation and I had thought that they were the cause for it not continuing.

 

[IceBreakerSours]

Have you run explicit analyses before? Do you know if your stent is sufficiently constrained? Not sure why you have multiple rigid plates; usually, these sims have a cylinder with BCs specified in a radial coordinate system.

Take a big step back and ensure: 1) BCs are applied as you expect in a test copy of this model. In that test copy, you could remove the stent altogether. If the crimping tool moves as per the BCs, great. 2) In another test copy, get rid of the crimping and apply a simple point load somewhere on the stent. Do you see stresses in that point load location or does the stent fly away? If the animation shows the stent flying away, your stent isn't constrained appropriately.