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5  Input file, initialization part

The initialization part contains initialization records and an end_initia record

initialization
...
initialization
end_initia
The example below initializes a solid material

echo -yes
number_of_space_dimensions 2
materi_velocity
materi_strain_total
materi_stress
end_initia
The echo (always the first record), number_of_space_dimensions (always the second record), and end_initia record should be supplied always. Use echo -yes to echo the input and echo -no to not echo the input. Use number_of_space_dimensions 1 for 1D problems, etc.. The records materi_velocity, materi_strain_total and materi_stress create a velocity, strain and stress field in the entire domain. In the following sections, all possible initialization records are discussed. Most of these records create an unknown field, a physical field like a temperature field or or a strain field, over the computational domain.

5.1  echo switch (first record of initialization part)

If switch is -yes the input will be echoed. If switch is -no the input will not be echoed. This needs to be the first record.

5.2  number_of_space_dimensions number_of_space_dimensions
(second record of initialization part)

Set number_of_space_dimensions to 1 in 1D, etc.. You can also use the short name ndim if you prefer. This needs to be the second record.

5.3  derivatives (third record of initialization part, if specified)

If this record is included, the time derivative and the space derivatives will be stored in the node_dof records. This is only required for a limited number of models. The model description will specify if this derivatives initialization is needed.

5.4  condif_temperature

The temperature T is added to the node_dof records.

5.5  groundflow_velocity

The ground water flow velocity vig is added to the node_dof records. Condition: the -groundflow differential group_type should be present.

5.6  groundflow_pressure

The pressure p is added to the node_dof records. Condition: the -materi or -groundflow differential group_type should be present.

5.7  materi_damage

The damage d is added to the node_dof records. Also materi_velocity and materi_strain_total should be initialized.

5.8  materi_density

The density ρ is added to the node_dof records. Now this density is used in the equations, and the data item record materi_density in the data part needs not to be specified. The density is governed by the mass conservation law

ρ +
∂ ρ vj
xj
= 0


where vj is the velocity in the direction of the space coordinate xj. Don't forget to initialize the density by specifying node_dof records. Condition: the -materi differential group_type should be present.

5.9  materi_diffusion

The artificial diffusion c is added to the node_dof records. It can be used in combination with materi_diffusion_minimum to decide in an eulerian calculation where material is present and where not. Initially set c to 0 at places where no material is present, and set it to 1 at places where material is present. The initialization needs to be done in the node_dof records.

The redistribution of diffusion is governed by the conservation law

c +
c vj
xj
= 0


where vj is the velocity in the direction of the space coordinate xj. Condition: the -materi differential group_type should be present.

5.10  materi_displacement

The displacements u,v,w are added to the node_dof records. If materi_displacement is initialized, then equations like the convection and diffusion of heat equation or the ground water flow equation are evaluated over the deformed volume, which is the sum of the nodal coordinates plus its displacements. Also if materi_displacement is initialized, the total lagrange model will be used in stress analysis.

Condition: also materi_velocity should be initialized because the displacement follows from integration of the velocity.

5.11  materi_history_variables number_of_variables

Generic history variables which can e.g. be used in some user supplied routines.

5.12  materi_maxwell_stress number_of_chains

Maxwell stress σ11m   σ12m   σ13m   σ22m   σ23m   σ33m is added to the node_dof records. The parameter number_of_chains should match data item group_materi_maxwell_chains. The number of maxwell stresses is 6 * number_of_chains. Condition: the -materi differential group_type should be present.

5.13  materi_plasti_f

The plastic yield rule f is added to the node_dof records.

5.14  materi_plasti_f_nonlocal

The nonlocal plastic yield rule fn is added to the node_dof records. See also: options_nonlocal.

5.15  materi_plasti_kappa

The plastic isotropic hardening parameter κ is added to the node_dof records. Condition: the -materi differential group_type should be present.

5.16  materi_plasti_rho

The plastic kinematic hardening vector ρ11   ρ12   ρ13   ρ22   ρ23   ρ33 is added to the node_dof records. See also group_materi_plasti_kinematic_hardening. Condition: the -materi differential group_type should be present.

5.17  materi_strainenergy

The material strain energy 0.5 σij єijelas is added to the node_dof records. You can print or plot it to see where energy is stored after loading. Also materi_stress and materi_strain_elasti should be initialised.

5.18  materi_strain_elasti

The elastic strain єklelas is added to the node_dof records. Condition: the -materi differential group_type should be present. See also: materi_strain_total.

5.19  materi_strain_intergranular

The intergranular strain Sij is added to the node_dof records. This can be used by hypoplasticity laws, see the theory section.

5.20  materi_strain_plasti

The plastic strain єklplas is added to the node_dof records. Condition: the -materi differential group_type should be present. See also: materi_strain_total.

5.21  materi_strain_total

The total strain єkl is added to the node_dof records. All strains are time integrals of the strain rates for a specific material particle which happens to be present in the node. Condition: the -materi differential group_type should be present.

5.22  materi_stress

The stresses σ11   σ12   σ13   σ22   σ23   σ33 are added to the node_dof records. Condition: the -materi differential group_type should be present.

5.23  materi_velocity

The velocities vi are added to the node_dof records. Condition: the -materi differential group_type should be present.

5.24  materi_velocity_integrated

The integrated velocities vii are added to the node_dof records. The integration of nodal velocities in fact results in displacements. But asking for these integrated velocities doesn't activate automatically that the calculation is done over the total deformed volume (as is the case when you initialize materi_displacement), and not automatically a total lagrange model is used in stress analysis.

Condition: also materi_velocity should be initialized because these are necessary for calculation materi_velocity_integrated.

5.25  materi_void_fraction

The material void fraction f* is added to the node_dof records. This is required for the group_materi_plasti_gurson model.

5.26  materi_work

The material second order work σij єij is added to the node_dof records. You can print or plot it to see where material instabilities are present.

5.27  residue

A scalar unknown is added to the node_dof records. The scalar is the residue in the differential equations. Also derivatives should be initialized.

5.28  wave_scalar

Scalar in wave equation is node_dof records. Condition: also wave_fscalar should be initialized and the -materi differential group_type should be present.

5.29  wave_fscalar

The first time derivative in the wave equation is added to the node_dof records. Condition: also wave_scalar should be initialized and the -materi differential group_type should be present.

5.30  end_initia (last record of initialization part)


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