2.2. Model Execution¶
Overview¶
A model in Matmodlab is defined by a MaterialPointSimulator object. The
MaterialPointSimulator object manages and allocates memory for materials
analysis steps. In this section, the MaterialPointSimulator object is
described.
The MaterialPointSimulator Object¶
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class
MaterialPointSimulator(runid, verbosity=1, d=None, inital_temperature=DEFAULT_TEMP, output='dbx')¶ Create a MaterialPointSimulator object and set up the simulation.
The runid string is the simulation ID. Generated files are named runid.ext, where ext is the file extension.
The following arguments are optional.
The verbosity integer set the simulation verbosity. Generally, 0=quiet, 2=noisy. The d string is the simulation directory, the default is the working directory. initial_temperature is the initial temperature, the default is 298 K. The output string specifies the output type, it defaults to dbx if not specified. See Matmodlab Output Formats for a description of supported output formats.
Examples:
>>> mps = MaterialPointSimulator('model') >>> mps = MaterialPointSimulator('model', verbosity=2, d='/home/user/sim')
Defining a Material Model¶
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MaterialPointSimulator.Material(model, parameters, name=None, switch=None, rebuild=False, param_names=None, source_files=None, source_directory=None, depvar=None, fiber_dirs=None, user_ics=False, order=None, response=None, libname=None)¶ Create and assign a material model
The required arguments are a model name and material parameters. The model name must be a recognized material model (see Material Library). parameters can either be a dictionary of key:value (key is the parameter name, value its numeric value) or ndarray.
The following arguments are optional and applicable to all materials.
rebuild is a boolean that, when True, forces the material model to be rebuilt before the simulation. switch is a tuple containing the material name and the name of another material to be switched in to its place.
The following arguments are applicable to user materials
source_files is a list of model source files. Each file must exist and be readable on the file system. If the optional source_directory is given, source files are looked for there. depvar is either the integer number of state dependent variables or a list of state dependent variable names. fiber_dirs is an array of fiber directions (applicable only to uanisohyper_inv models). param_names is a list of parameter names. If user_ics is True, Matmodlab calls the user supplied SDVINI subroutine to initialize state dependent variables - otherwise they are set to 0. order is a list of strings specifying the component ordering of second order tensors. response is one of “mechanical”, “hyperelastic”, or “anisotropic hyperelastic” and is used to determine which type of response the model will describe.
Examples:
>>> mps.Material('elastic', {'K': 123e9, 'G': 53e9}) >>> mps.Material('umat', (10e6, .333, 42e3), source_files=('umat.f', 'umat.pyf'), param_names=('E', 'nu', 'Y'), user_ics=True, depvar=('EQPS',))
Optional Material Addons¶
Thermal Expansion¶
An Thermal Expansion object, enabling the computation of thermal strains associated with thermal expansion.
Viscoelasticity¶
A Viscoelasticity object defining the linear relaxation response of the material. When given, the elastic moduli are treated as the instantaneous values.
Time-Temperature Shift¶
Used in conjuction with a Viscoelasticity to compute a reduced time.
Defining Simulation Steps¶
The recommended way to create simulation steps is to use the following convenience functions.
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MaterialPointSimulator.StrainStep(*)¶ All step components are interpreted as components of the strain tensor.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
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MaterialPointSimulator.StrainRateStep(*)¶ All step components are interpreted as components of the strain rate tensor.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
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MaterialPointSimulator.StressStep(*)¶ All step components are interpreted as components of the stress tensor.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
Note
kappa is set to 0 for stress steps
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MaterialPointSimulator.StressRateStep(*)¶ All step components are interpreted as components of the stress rate tensor.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
Note
kappa is set to 0 for stress rate steps
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MaterialPointSimulator.DisplacementStep(*)¶ All step components are interpreted as components of the displacement vector, applied only to the “+” faces of a unit cube centered at the coordinate origin.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
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MaterialPointSimulator.DefGradStep(*)¶ All step components are interpreted as components of the deformation gradient tensor.
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MaterialPointSimulator.DataSteps(filename, tc=0, columns=None, descriptors=None, skiprows=0, comments='#', sheet=None, *)¶ Generate steps from a data file.
filename is the name of a file containing the data. tc is the integer index of the column containing time. columns are the indices of the columns containing data. If not given, columns is taken to be the first six columns of the file, that are not tc.
skiprows is the integer number of rows to skip before reading data, comments is the comment delimiter. sheet is the sheet from which to read data, if filename is an excel file.
The ith descriptor designates the physical interpretation of the ith. descriptors must be one of ‘E’ (strain), ‘D’ (strain rate), ‘S’ (stress), ‘R’ (stress rate), ‘P’ (electric field), ‘T’ (temperature).
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
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MaterialPointSimulator.MixedStep(descriptors=None, *)¶ All step components are interpreted as components of stress and/or strain.
The ith descriptor designates the physical interpretation of the ith. descriptors must be one of ‘E’ or ‘S’ with ‘E’ representing strain and ‘S’ representing stress.
The arguments represented by the * are common to all other step methods and are described in Common Step Arguments.
Common Step Arguments¶
The arguments common to all step functions are:
components are the components of the tensor defining the step. Tensor ordering is described in Matmodlab Conventions. For all tensors, the components are assumed to be the “tensor values”, as opposed to the “engineering values”. For symmetric tensors, specifying only the three diagonal components implicitly assigns the off-diagonal components a value of zero. For strain type tensors, if only a single component is given, it is assumed to be a volumetric deformation. For stress type tensors, if only a single component is given, it is assumed to be a pressure.
scale is a multiplier applied to all components. It can be a float or a numpy ndarray (so that a different scale could be applied to each component separately).
frames is the integer number of increments that the step is subdivided in to.
kappa the Seth-Hill strain parameter. See The Strain Tensor for details.
temperature is the temperature. If not specified, the step is assigned the same temperature as the previous step.
elec_field is the electric field vector. If none is given, it is set to (0, 0, 0).
num_dumps is the integer number of times to write the output database. If not specified, all step increments are written.
Running the Simulation¶
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MaterialPointSimulator.run(termination_time=None)¶ Run the simulation
termination_time is the termination time. If not given, the final time from the last step is used.