Adjusting Advanced Solver Settings for the Numerical Execution Mode

You can adjust a set of tolerances and solver settings to control the accuracy and performance of the material response calculation in the numerical execution mode. The default values can provide good general performance for most material models and test data. However, you might want to modify the values to suit your specific material model or test data.

See Also
Best-Fit Error Measures
Calibration Algorithms and Parameter Sensitivity
  1. From the Calibration Tools section of the action bar, click Calibration Options .
  2. From the commands section at the top of the Calibration Options dialog box, click Optimization Controls .
  3. Expand the Advanced solver settings, and adjust the values for any of the following settings:
    OptionDescription
    Maximum strain increment Maximum allowable increment in the primary driving strain variable. If this value is less than a strain increment (▵εi=εi−εi−1) in your test data, the app computes the material response at a set of intermediate strain values between εi-1 and εi that respect the maximum allowable strain increment.
    Maximum inelastic strain rate increment Maximum difference in the creep strain increment calculated from the creep strain rates based on conditions at the beginning and the end of the increment. Therefore, this increment controls the accuracy of the creep integration.
    Minimum time increment The smallest time increment allowed during the calibration. For test data sets with very small time increments, the default value for this setting might be too large to ensure convergence. This setting should be smaller than the smallest time increment in all of the test data sets.
    Relative toleranceThe numerical execution mode uses a Newton loop to enforce stress constraints that depend on the deformation mode. The app uses the relative tolerance setting as convergence criteria for the loop. For example, if you are computing the material response for uniaxial tension data, the app considers the Newton loop to be converged when the absolute value of the ratio of the lateral stress to the uniaxial stress is less than the specified relative tolerance. Numerical execution mode does not use the relative tolerance check for simple shear because this mode is completely kinematically constrained.
    Maximum number of Newton iterations Maximum number of allowable Newton iterations before the app requests a cutback.
    Maximum number of cutbacks Maximum number of allowable sequential cutbacks before the app abandons the material response calculation.
  4. Close the panel.