Material Model for Hyperelastic Material Definition

After you enter the stress and strain data in the test area, use the Show Best Fit Material Model Curves option to examine how closely the different material models approximate the test data. Select the check box for any material model in the Show Best Fit Material Model Curves area. For each selected material model, Creo Simulate draws a curve in the graph area. The curve represents the model’s best fit to the test data.

To learn more about how Creo Simulate generates the best fit for the test data, see Guidelines for Fitting the Material Model.

You can select any one of the following material models to generate the best fit curve:

• Yeoh

To change the color of the curve, use the Data Series tab of the Graph Window Options dialog box.

Creo Simulate displays RMS Error for every selected material model. The RMS Error is the difference between the model’s stress-strain curve and the test data. When Creo Simulate can not generate the best fit curve for any material model, the RMS Error column displays NA for the material model. Creo Simulate may not generate the best fit curve for a material model, if the stress-strain data specified in the tests area is insufficient.

A red exclamation mark, , may appear for any material model. This exclamation mark indicates that the material model is invalid for a certain value of the strain in the range between -0.9 and 9.0. You can ignore the red exclamation mark and use the material model. However, you must ensure that the material model is valid in the strain ranges that the material experiences during the analysis. When you select an invalid material model and click OK on the Hyperelastic Material Definition dialog box, Creo Simulate displays strain ranges in which the material model is invalid.

By default, the list of material models in the Select Material Model area displays Automatic. This indicates the automatic selection of the material model. Creo Simulate selects a valid material model that has the minimum RMS Error. Alternatively, you can select any other material model from the list in the Select Material Model area. When you select a material model, make sure that the best fit curve for the material model is available in the graph area.

The name of the selected material model and values of its coefficients appear in the Select Material Model area. Creo Simulate uses the best fit curve to calculate these values. To change the values, clear the Use Best Fit Coefficients check box and specify the values of coefficients. When you change the values of the coefficients, the stress-strain curve for that material model changes in the graph area.

When you click OK on the Hyperelastic Material Definition dialog box, Creo Simulate uses the coefficients to define the hyperelastic material. The name of the material model and coefficients appear in the Material Model section of the Material Definition dialog box.

Return to Hyperelastic Material Definition.