# Numerical Solution - Lesson 6

As per FDA recommended submission guidelines for stents, the model needs to be set up to provide outputs of recoil percentage, peak stresses, and residual stresses from deflation and contact separation.

Text Summary of the Above Video:

•  Solution
• Insert > Stress > Equivalent
• Insert > Deformation > Total
• Press 'Solve'

Note

This simulation is considerably heavy. It took us almost 2 hours to run it, on a powerful workstation.

The Recoil Percentage is calculated by probing the deformation of one point on the stent and subtracting the max. displacement by the value after relaxation. This will then be divided by the max. displacement, to reach a percentage of recoil with relaxation.

The Peak Stress is measured at the max. displacement of the stent, using the Von-Mises equivalent stress criterion.

Similarly, the Residual Stress is measured using the Von-Mises criterion but is measured after balloon and stent relaxation, to find the total stress as a result of plastic deformation.