Migrating from v2.1.1 to v2.1.2

Input file changes

Variable naming: subspace prefixes removed

The most pervasive change in v2.1.2 is the removal of LabeledAxis. Variables no longer carry state/, forces/, residual/, or state/internal/ prefixes anywhere in input files.

Every option that previously accepted a prefixed variable name (e.g. tensor, variable, from, to, invariant, cauchy_stress, temperature, stress, etc.) now takes the bare variable name without any prefix.

History variables renamed (~N suffix)

“Old state” (history) variables, previously named under old_state/ or old_forces/ sub-axes, now use a ~N suffix where N is the lag order:

v2.1.1 name	v2.1.2 name
old_state/S	S~1
old_forces/E	E~1

If you reference history variables explicitly (e.g. in a ComposedModel’s additional_outputs list or a custom model), update those names accordingly.

NonlinearSystem: unknowns is now required

In v2.1.1, NonlinearSystem inferred its unknowns from the model’s state input sub-axis. In v2.1.2, you must list the unknown variables explicitly:

# v2.1.1
[EquationSystems]
  [eq_sys]
    type = NonlinearSystem
    model = 'implicit_model'
  []
[]

# v2.1.2
[EquationSystems]
  [eq_sys]
    type = NonlinearSystem
    model = 'implicit_model'
    unknowns = 'ep Ep'
  []
[]

Residual variable names default to <unknown>_residual for each unknown. Override with the residuals option when needed:

[EquationSystems]
  [eq_sys]
    type = NonlinearSystem
    model = 'implicit_model'
    unknowns = 'phi_P phi_S'
    residuals = 'phi_P_residual phi_S_residual'
  []
[]

SDTSolidMechanicsDriver / LDISolidMechanicsDriver removed

These convenience driver types were removed. Use TransientDriver directly and supply the strain/stress controls through the generic force_SR2_* options.

Strain-control (formerly SDTSolidMechanicsDriver):

# v2.1.1
[Drivers]
  [driver]
    type = SDTSolidMechanicsDriver
    model = 'model'
    prescribed_time = 'times'
    prescribed_strains = 'strains'
    save_as = 'result.pt'
  []
[]

# v2.1.2
[Drivers]
  [driver]
    type = TransientDriver
    model = 'model'
    prescribed_time = 'times'
    force_SR2_names = 'strain'
    force_SR2_values = 'strains'
    save_as = 'result.pt'
  []
[]

For mixed-control (formerly LDISolidMechanicsDriver), use the same pattern with the appropriate force_SR2_names / ic_SR2_names values for your control mode.

Predictor moved from TransientDriver into ImplicitUpdate

The predictor, custom_predictor, and custom_predictor_apply options have been removed from TransientDriver. Predictors are now ordinary model blocks in [Models] and are referenced from ImplicitUpdate via a new predictor option.

Before (v2.1.1):

[Drivers]
  [driver]
    type = TransientDriver
    model = 'model'
    prescribed_time = 'times'
    predictor = 'PREVIOUS_STATE'   # or LINEAR_EXTRAPOLATION, or via custom_predictor
    # ...
  []
[]

[Models]
  [model]
    type = ImplicitUpdate
    equation_system = 'eq_sys'
    solver = 'newton'
  []
[]

After (v2.1.2):

[Drivers]
  [driver]
    type = TransientDriver
    model = 'model'
    prescribed_time = 'times'
    # predictor option removed
  []
[]

[Models]
  [predictor]
    type = ConstantExtrapolationPredictor
    unknowns_SR2 = 'stress'
    unknowns_Scalar = 'equivalent_plastic_strain'
  []
  [model]
    type = ImplicitUpdate
    equation_system = 'eq_sys'
    solver = 'newton'
    predictor = 'predictor'
  []
[]

Choosing a predictor type

v2.1.1 driver option	v2.1.2 predictor type
predictor = 'PREVIOUS_STATE'	ConstantExtrapolationPredictor
predictor = 'LINEAR_EXTRAPOLATION'	LinearExtrapolationPredictor
custom_predictor = '<name>'	keep the existing model block; wire it with predictor = '<name>' on ImplicitUpdate
(no predictor in driver)	ConstantExtrapolationPredictor