Define Stress versus Strain Curve

Define a stress versus strain curve that is referenced by a non-linear material property.

SimSolid assumes an engineering stress-strain curve.
Engineering stress
Assumes a constant non-changing cross-section area during deformation.
True Stress
Assumes the cross-section area that changes at every instant during deformation.

Some sources use true stress-strain curves. They can be imported by SimSolid from a CSV file.

  1. In the Settings menu, click Material Database.
  2. In the dialog, select a material and click Edit material.
  3. Select Add Stress-strain curve.
  4. In the Stress-strain curve dialog, use one of the following ways to define a stress-strain curve:
    Import from CSV
    1. Click Import CSV.
    2. In the File browser, choose the desired CSV and click Open.
    Create from N-values Create stress-strain curve using a K-n power law function.
    • Click Create by n-value.
    • Specify K and n.
    Some sample K-n values for typical materials are given in the drop-down menu.
    Create manually
    • Click Add row.
    • Enter the stress and strain values. At minimum, 3 points are required.
    The results are plotted in the XY graph in the dialog. You can use the scroll wheel to zoom in, the left mouse button to pan, or the Refit button to reset the graph.
  5. Optional: Click Edit elasticity modulus to update the elasticity modulus of a selected material.
    The stress-strain curve is automatically updated to reflect the elasticity modulus entered.
    If the elasticity modulus defined is less than the elasticity modulus derived from the curve, the stress-strain curve is trimmed by intersecting the line that defines the new elasticity modulus and the stress-strain curve.
    Note: If an x-value input is outside the range of x-values specified on the Table, the corresponding y-value look up is performed using linear extrapolation from the two end points.

CSV File Format

CSV Fields

The format of the file has a header "strain, stress" and corresponding row of values. If the data is true stress-strain, add [true] to the end of the header row:

stress, strain, [true]

Note: The data will be converted to engineering stress-strain as the .csv file is read in.

Example File (elastic-perfectly-plastic.csv)


Example File (elastic-plastic-line-hardening.csv)