Passive Cube

Description

  • This example guides you through setting up and running a physical and material nonlinear bi-axial stretch test of a passive (non-contracting) cube using displacement boundary conditions.
  • The mesh is a simple one-element cube with tri-linear basis functions. The boundary conditions assure that all rigid body motions are suppressed, and that the cube is stretched in two perpendicular directions. The material chosen is a transversely isotropic exponential strain energy function. The material is stiffer in the fiber direction than perpendicular to them.

Start Continuity

  • Launch the Continuity Client
  • On the About Continuity startup screen

    • Leave the mesh checkbox checked under Use Modules:

    • In addition, check the biomechanics checkbox

  • Click OK to bring up the main window

Create mesh

Add biomechanics data

  • Load the required biomechanics model from the database
    • File→Library→Search...
    • In the window near the top, enter 'lagrangian' and hit return.

    • From the listed models select BM_TI_of_Lagrangian_strains_comp_sympy by right-clicking on it and selecting 'Load'

    • When the warning window display, select the third choice: 'Retain current problem but overwrite the following objects: [dims, renderer, matEquations]'
  • Biomechanics→Update→Initial conditions with undeformed nodes

  • Biomechanics→Edit→Boundary Conditions...

    • Click on the Deformed Coordinates 1 tab

      • Click the Insert Nodes button two times

      • Click on node 1 in the list

        • Enter 1,3,5,7 in the Node(s) text field, and hit Enter

      • Click on node 2 in the list

        • Enter 2,4,6,8 in the Node(s) text field, and hit Enter

        • Enter 0.25 in the Value text field

    • Click on the Deformed Coorinates 2 tab

      • Click the Insert Nodes button two times

      • Click on node 1 in the list

        • Enter 1,2,5,6 in the Node(s) text field, and hit Enter

      • Click on node 2 in the list

        • Enter 3,4,7,8 in the Node(s) text field, and hit Enter

        • Enter 0.25 in the Value text field

    • Click on the Deformed Coorinates 3 tab

      • Click the Insert Nodes button four times

    • Click the OK button

  • File→Send

    • If the Dimensions Form appears, simply click Apply Marked Recommendations and then OK

  • Mesh→Calculate Mesh...

  • Biomechanics→Solve Nonlinear...

    • Change the Time Step to 0.1

    • Change the Number of Steps to 10

    • Click the Solve button, and wait for the solver to finish its job

  • Mesh→Render→Elements...

    • Click the lines radio button

    • This time select the deformed radio button is selected

    • Click Render to display mesh lines

  • The mesh should now look like the following screenshot:

Pre-built model

This cont6 file contains all data and parameters for this problem, right before the biomechanics solve: bm1.cont6