Stent forces simulation

[ryankb]

I've seen a few other threads on here about how to calculate the reaction forces on a nitinol stent - but I think I'm missing something (I've never been great at post-processing navigation in Abaqus).

I have a simple nitinol stent. Expanded out, annealed, then crimped. I want to create a plot showing the total reactive crimp forces vs. diameter. I also have another where I want to show the force the stent exerts on the expansion cylinder as it is being expanded. I imagine it's nearly the same process for both, but with a slight variation.

How can I accomplish this? I tried exporting the X-Y data of the Reaction force magnitude, but this gave me three very long lists of nodal information at a single timestep. I'm not sure how the three columns are different as I requested "magnitude" and not the components, but I digress.

I saw Dave442 gave a similar instruction in this thread:

http://www.eng-tips.com/viewthread.cfm?qid=408166

but I'm afraid I do not understand how to complete either task he mentions:

"You need to sum the radial reaction force at each node on your rigid surface at each increment to obtain the force response over time. You can figure out the diameter values from the starting diameter of the rigid surface and the applied displacements. Alternatively, you can simplify this task significantly by using a reference point and *Equation to control the rigid surfaces. That way, you can just plot the radial reaction force for the reference point during the analysis (no summation required)."

Any help with executing the above statement by Dave would be very much appreciated.

 

[Dave442]

when you extract reaction forces for the crimp surface you get RF1, RF2 and RF3 at every node on the entire surface. These results are calculated with respect to the global coordinate system. To calculate total radial force you would need to first transform to a polar coordinate system and then sum RFX where X is the radial direction for your model/assembly.

The alternative method I mentioned is to use *equation to constrain U1, U2 and U3 of all nodes on the crimp surface to U1, U2 and U3 of a reference point. By doing this, any displacements applied to the reference point are applied to every node on the crimp surface. Similarly, any reaction forces observed at nodes on the crimp surface are automatically summed and reported at the reference point.

*equation is used to define a linear constraint equation and is described pretty well in the documentation.