How to apply displacement to specific nodes of a TetrahedralMesh?

[AlanConnorChen]

Hello,

I want to apply displacements (which can also be seen as external forces) to some specific 3D points(with their indices provided) of a Tetrahedral Mesh and model the entire Tetrahedral Mesh as a HyperElastic FEM Model, such as the ones listed here: tetrahedronhyperelasticityfemforcefield

The goal is to set the target positions for the deformation of these 3D points and obtain the deformed model. The displacement vectors are shown in the figure below.

Here are my questions:

1. To achieve the above goal, what resources should I refer to? I noticed the documentation here: pointprojectiveconstraint Can this help me achieve the desired result?

2. Additionally, I’m facing another issue where I can’t import my own .vtk file after I drag my .scn file into the gui. The SOFA interface appears blank, but there are no error messages in the terminal. My screenshot and console logs are as follows.
   
   console_log.txt

The .scn file and .vtk file I’m using are available in the google drive. Thanks in advance.

[bakpaul]

Hello

This is fairly easy to do. You can use BilateralLagrangianConstraint to impose the position of a subset of points of the model. See here an example : https://github.com/sofa-framework/sofa/blob/master/examples/Component/Constraint/Lagrangian/BilateralLagrangianConstraint_NNCG.scn

In this example all of the objects are simulated, but one of the two inputed object can be only a node containing a MechanicalStatethat contains the target points without any solvers of mechanics attached. Make sure to put this node in the rootNode, not as a child of any of the node of your liver.

Tell me how it goes !

[AlanConnorChen]

Hello

Thank you for your reply, sorry for the late response. I have already opened the example file and observed its simulation effect.

As for the BilateralLagrangianConstraint you mentioned, I am still thinking about how to process and import my own VTK file, and I am currently still in the exploration process.

Thank you for your reply!