Reply To: under relaxation factor

[Rahul]

Okay. Here you can apply it on force data transfer. 
How good is the mesh? Ensure that you have good mesh quality.
What is your working fluid? I assume you are using a liquid (blood) for your application. Make sure your material is set as a compressible liquid. An incompressible fluid will have infinite sound speed, which in cases with deforming fluids can lead to pressure spikes at the FSI interfaces resulting in excessive deformation. If you still experience high pressure oscillations at the FSI interface, consider using Solution Stabilization 12.6.9.8 Solution Stabilization for Dynamic Meshes Boundary Zones (ansys.com)