Example Input Syntax

[stress]
  type = NEMLStress
  model = simple_example
  database = 'examples.xml'
[]

The standard usage of NEMLStress is shown in this input file, where all material properties are provided in the xml file as shown:

<materials>

 <simple_example type="SmallStrainElasticity">
   <elastic type="IsotropicLinearElasticModel">
     <m1_type>youngs</m1_type>
     <m1>100000</m1>
     <m2_type>poissons</m2_type>
     <m2>0.30</m2>
   </elastic>
   <alpha>1.0e-4</alpha>
 </simple_example>

A NEML xml file starts with the xml root <materials> and with in this root, multiple material models are defined within separate xml elements. This example xml file contains three material models, i.e. simple_elastic, variable_example, complex_example. The model keyword is used to select a particular model from the NEML xml file. The model name in the xml file is given in the xml tag that that begin and end the xml element. The xml tag containing the material model also contains the model type.

Example Input Syntax with Parameter Substitution

[stress]
  type = NEMLStress
  database = 'examples.xml'
  model = variable_example
  neml_variable_iname = 'PoissonsVar YoungsVar'
  neml_variable_value = '0.3         100000'
[]

Alternatively, this input file uses optional parameters that allow some of the NEML model parameters that would ordinarily be defined in the xml file to be defined in the MOOSE input file. This option is provided to allow selected values to be varied for sampling using the stochastic_tools module. The numerical values that are ordinarily used in the NEML xml file must be replaced by unique string identifiers enclosed in {}, which are then referenced in the neml_variable_iname parameter in the MOOSE input file. In this example, these identifiers are PoissonsVar and YoungsVar.

 <variable_example type="SmallStrainElasticity">
   <elastic type="IsotropicLinearElasticModel">
     <m1_type>youngs</m1_type>
     <m1>{YoungsVar}</m1>
     <m2_type>poissons</m2_type>
     <m2>{PoissonsVar}</m2>
   </elastic>
   <alpha>1.0e-4</alpha>
 </variable_example>
 

The numerical values that get substituted for the identifiers defined in neml_variable_iname are prescribed using the neml_variable_value0 through neml_variable_value7 parameters. The numbers at the end of these parameters indicate the position in the neml_variable_iname vector of the identifier to be substituted. Up to 8 parameters are allowed to be defined in this way. These are specifed using separate parameters, rather than in a vector, to allow for their values to be sampled using stochastic_tools which does not currently support modifying parameter vector entries.

Input Parameters

Input Files

• (test/tests/neml_stochasticSimple/le_stress_simple.i)
• (test/tests/neml_benchmark/linear_strain_hardening/elas_plas_LSH_neml.i)
• (test/tests/neml_simple/le_stress_thermal.i)
• (test/tests/neml_complex/inelastic_dt.i)
• (test/tests/neml_complex/inelastic.i)
• (test/tests/neml_benchmark/power_law_creep/nafems_test5a_lim_neml.i)
• (test/tests/neml_simple/le_stress.i)
• (test/tests/neml_regression/neml_regression.i)
• (test/tests/neml_simple/le_stress_variableOverwrite.i)

References