Troubleshooting

Failed calibrations or unphysical results are typically due to one of the following:

• The Material Calibration application is unable to connect to the Ansys Material Calibration Service. Check the connection to your Ansys Material Calibration Service server, and try again.
• Test data has been imported from a file which is not based on a Consistent Unit System.
• A multi-step process is recommended when fitting the combination models (for example, Hyperelastic Ogden + Viscoelastic Prony Shear):
  • Step 1: Use the loading portion of the test data (typically uniaxial test data) to fit the hyperelastic model parameters accurately. Initialize the parameters appropriately to obtain a meaningful fit. Copy the fitted parameters.
  • Step 2: Input the fitted parameters of the hyperelastic model from Step 1 as ‘fixed’ values, and use the test data containing both the loading and relaxation portions to fit the viscoelastic (or Prony series) model parameters.
  • Step 3: Optional - Validate the fit by comparing with test data of any other type (for example, biaxial tension).
• Inappropriate or unphysical coefficient values or upper/lower bounds. Ansys recommend using Initialize to help refine your starting point before calibrating.
• For Arruda-Boyce, Bergstrom-Boyce, Gent, Ogden, Ogden Foam, and Three Network hyperelasticity models, the initial values supplied must be fairly close to the end result to ensure a good fit. Use the preview or Initialize features to help refine your starting point before calibrating.
• Inappropriate fitting parameters. The default values provided by the Ansys Material Calibration Service are shown in Calibrate test data.