Verification & Validation - Lesson 8

Mesh Refinement

First, we'll check that we can get convergence of the solution by refining the mesh. By decreasing the size of the elements on the body of the stent, we can increase resolution for the solution; We change the element size for the Stent to .025 mm and the Balloon to .035 mm, and retrieve the following solutions for Stresses and Displacement;

Peak Stress (MPa)
Peak Displacement (m)
Original Mesh (4624 Elements) 2.6538e8 4.0676e-5
Refined Mesh (13875 Elements) 2.1095e8 4.0796e-5

And we can see that the peak stresses and displacements are not exploding to large numbers, but rather are converging to finite values.


Validation with academic papers, industry data

In examining our model's requirements under FDA guidelines, it is useful to check that our solution has values that are similar to other accepted industry stent designs. Some examples from industry stents are shown below, alongside our values;

Recoil %
Peak Stress (MPa)
Max Residual Stress (MPa)
Jostent Flex ® 5.3 314.8 219.7
Multi-Link Ultra ® 3.1 336.3 228.6
SimCafe Stent 6.8 265.4 162.4

We can see that in comparison with other stent designs, ours has similar values, and so we can have some confidence that our model approach was correct.