Create an Incompressible Hyperelastic File

This tutorial povides step-by-step instructions for fitting an incompressible hyper-elastic material using AMM.

The process includes selecting the correct workspace, importing material data, fitting various hyperelastic properties, preparing and reviewing the file for export, and exporting the file.

Step 1: Select Material General Information

  1. Launch AMM and select Polymer.
  2. Select the Project Folder from using the pop-up window. The application automatically sets it as a thermoset when hyper-elastic fitting material data is chosen.
    Figure 1. Material Modeler Objective

    Material Modeler Objective
  3. Provide the Material General Information. Enter a Material Name to identify the material being characterized. For example, Natural Rubber.

    The Material Class: Polymer-Thermoset and Chemical Family: PBR is auto-set with the imported material data.

    Figure 2. Material General Information

    Material General Information
  4. Choose one of the following options:
    • Enter a Material Manufacturer’s name.
    • Click to view the list of material manufacturers. Select the required material manufacturer from the list. For example, Public Reference Data.
  5. Enter a Data Source name. For example, Treloar Paper.
    1. The Data Last Updated displays the last updated date of the material model. By default the current date is displayed.
    2. Enter any reference Notes of the material model.

Step 2: Import, Fit and Approve Hyperelastic Data

The Material Test File List and file type values are auto-populated based on the selected Objective workflow. Default file types can be changed if the data for import is different than the selection.

  1. Select Hyperelastic in Material Test File List and import an Excel data file that contains uniaxial test data.
    Note: The supported tests are Uniaxial (UXT), Equibiaxial (EBT), and Pure Shear/ Planar (PLN).
    The Hyperelastic Data Import - Details pop-up window is displayed. Select the units and curve paramaters. For this exercise, continue with the default Engineering Stress and Strain values.
    Figure 3. Hyperelastic Data Import - Details

    Hyperelastic Data Import - Details
  2. Select the Data Source specified (i.e., Excel file) that contains unixal test data. The system loads a single curve fitting for the material.
    Note: Single Curve Fitting models that contains NEOH (Neo-Hookean), MRIV (Mooney-Rivlin), SIGN (Signorini), YEOH (Yeoh), GENT (Gent), and ARBY (Arruda-Boyce).

    Multi-Curve Fitting Models include YEOH (Yeoh), MRV9 (General Mooney (Polynomial)), 9-Parameter, and OGDN (Ogden) N=3 is planned for future release.

    Figure 4. Treloar Paper - Uniaxial Data - Engineering Stress & Strain

    Treloar Paper - Uniaxial Data - Engineering Stress & Strain
  3. Modify the fitting material parameters data.
    1. Isolate specific models like ARBY and YEOH models.
    2. Modify YEOH parameters such as coefficients (e.g., set a value to C20: -0.052 and C30: 0.000294).
    Figure 5. Engineering Stress & Strain for ARBY and YEOH Models

    Engineering Stress & Strain for ARBY and YEOH Models
  4. Evaluate the curve changes affect the fit of the material model.
  5. Switch between different views, such as Engineering Stress & Strain or True Stress & Strain to see how the curve's shape changes.
    Figure 6. True Stress & Strain

    True Stress & Strain
  6. Select Save Changes to save changes made to the coefficients.
  7. Load a second data file, equi-biaxial material data.
  8. After import, toggle between the uniaxial and equi-biaxial data for comparison and make necessary changes.
    Note: The current beta release only allows to export the single curve fitting not multiple curve fitting.
  9. Select the Approve Model Fit checkbox to approve and save the settings.

Step 3: Prepare for Export and Preview Material Fit Data

Before exporting, review the settings such as:

  1. On Material Overview > File Management pane, modify the Unit System as required.
  2. Preview the material model and incompressible parameter values for Poisson Ratio, Density, and Temperature are displayed.
    Note: The application displays most relevant values for each parameters.
    Figure 7. Incompressible Paramater and its Values

    Incompressible Paramater and its Values
  3. If required, edit to finalize the export fit data. Select and delete the extra model information from the preview that are not relevant.
    Figure 8. Preview Model Fit Data

    Preview Model Fit Data

    The Optistruct options are displayed in the preview.

  4. Retain the YEOH data for the Optistruct model with the changed coefficient values.
  5. Rename the Export File Name.
    Figure 9. Export Material Fit File Data

    Export Material Fit File Data
  6. Click Export File. The application displays a message on the export file name and location.