How to expand one solid body inside another solid body?

Shae2021Shae2021 Member Posts: 1

I want to open an artificial valve inside an aortic valve. But before that I am trying to open (push) the leaflets with a cylinder (images are attached). 

The material assigned to leaflets and the middle cylinder is Polyethylene. I want to assign air to root but ANSYS shows an error that Elasticity is required (while Air has no elasticity).

Contacts -- A frictionless contact was used between the cylinder and the leaflet


The faces where leaflets are attached to the root have fixed supports

Cylinder has a displacement support.

I assigned different materials to the root, but the simulation stops at the start. Any idea how to expand one solid body inside another solid body?

Thank you!


  • KaiKai Posts: 105Forum Coordinator

    Hi, why would you like to assign air to the root? If the root is not having any mechanical effects, can you just not modeling it (e.g., suppress it in Mechanical)?

  • Shae2021Shae2021 Posts: 2Member
    edited April 4

    Hi Kai, I fixed the previous problem. I created a surface (shell) from root faces then gave it a thickness and suppressed root body. I need to expand that cylinder (or balloon) inside the root. The cylinder should push the leaflets as it expands and it should stop when leaflets are open. Cylinder should not penetrate the leaflets or the root.

    I am using transient structural. Balloon and leaflets have hyperelastic materials. I’ve tried frictionless, frictional and boded contacts between the cylinder and leaflets. None of them have been successful in moving/pushing the leaflets. Additionally, I used the following settings

    Formulation: Normal Lagrange - allows zero penetration

    Detection method: Nodal-projected normal from contact

    Interface treatment: Adjust to touch

    Solver type : direct

    Large deflection: on

    Auto time stepping : on

    I tried pressure (0.4 MPa) and displacement (8mm) separately on both the shell cylinder and the solid body cylinder. With a small cylinder (cylinder not touching the leaflets) I was unable to push the leaflets by inflating/expanding the cylinder. But if the cylinder touches the leaflets (like the pictures in my previous post), inflation of the cylinder pushes the leaflets.

    What do you think goes wrong in the contacts or the setup of this simulation? Thanks!

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