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Analyze stent expansion under pressure, modeling as a folded cylinder, applying axial and circumferential forces, using symmetry boundary conditions and coupling degrees of freedom for accurate results.
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Assignment 3 Stent expansion analysis
Relating 2d to 3d • Pressure applied to balloon – transmitted to stent • Balloon is initially folded Cylinder under internal pressure Circ. force Circ. dist R P Axial distance Circumferential force, F = PR CHECK UNITS! This is per unit axial length
Using symmetry BCs • We assume stent can be modelled as:
Using symmetry BCs • Constrain DOFs on symmetry boundaries Ux = 0 ?? ?? y Uy = 0 x
Coupled DOFs • To allow an arbitrary displacement but fix all nodes to have the same value, use CP command: NSEL,s,loc,x,LENGTH CP,1,ux,all or Preprocessor>Coupling / Ceqn>Couple DOFs
Deforming the strut • Either: • Apply a known force and calculate the displacement • Or: • Apply a displacement and calculate the resultant force, using: FSUM command General Postproc>Nodal Calcs>Total Force Sum