Altair Material Modeler (AMM) is specialized CAE software powered by COMPOSE technology. It rapidly and accurately
generates simulation-ready material cards for nonlinear bulk materials like metals and plastics, using raw test data.
AMM provides multiple mathematical models for curve fitting and extrapolation according to solver requirements. Additionally,
the expert mode enables you to create strain-rate curves, failure criteria, and run validation simulations.
Each prepared curve is displayed in the Curve Fitting list. Select the desired curve
for fitting.
Choose the most appropriate approach and select the range of the x-axis
(default value is 100%) and then click Curve Fit.
Each fit is listed in the Extrapolation field. The corresponding curve
is plotted in the graph for validation. The Spline option starts a special tool
for creating splines.
Figure 1. Corresponding Curve plot for Validation
Select a curve in the Extrapolation field. The curve
will zoom in and plot the derivative. This indicates:
Derivative curve is below the hardening curve material is stable.
Derivative curve is above the hardening curve material is unstable.
Note: Use Save Curve if you are fine
with the fitting solutions.
Select one more fitting curve by holding down the control key and clicking with
the left mouse button. Adjust the ratio between both curves using the slider. If
you are satisfied with the result, click Combine and
Save.
Figure 2. Combine and Save the Curves
Spline is special tool for creating splines. Select the
Spline check box, a new window displays with the
actual selected curve. You can start redrawing a smoothed curve on the existing
curve and re-interpret the hardening curve by adding new points on the existing
curve.
Interpret and manually add six points, the spline appears, and the line is
drawn. Select further points to extrapolate to 100% (or beyond). The dashed
curve shows the 1st derivative of the spline.
The crossing points indicate the stability points:
Figure 3. Spline Extrapolation
Optional: You can further modify the curve by adding new control points or moving
existing ones. The derivative curve is updated to reflect the changes in terms
of the numerical material behavior.
Hardening curves created by spline fitting cannot be used in combination with
curves created by extrapolation methods.