Initial Conditions

Initial Conditions

 

Description

 

Here are described the Keywords and options for prescribing initial conditions to a problem. This is generally used to create ParaGeo Spatial Grids with input values for state variables.

 

 

Click to expand/collapseDISTRIBUTION    Distribution values of material properties

Usage

*DISTRIBUTION,  NAME=Distribution_Table_Name, LOCATION=Element_or_Node, TABLE=Table_name  

Description

Defines initial values to material  state variables (e.g. Young modulus, Poisson Ratio, Porosity etc.) defined in a *DISTRIBUTION TABLE  which is assigned to the present *DISTRIBUTION  name.  This data is used to create a Spatial_State_set in ParaGeo. Following *DISTRIBUTION keyword and all its corresponding parameters the input format of the values should be as comma separated values with as many rows as required as follows:

 

Value 1

Value 2

Value 3

...

Value n

Node/Element number

Property 1 value

Property 2 value

...

Property "n" value

 

 

Compulsory Parameters

NAME

Defines a name for the distribution set so it can be refereed.

LOCATION

Defines whether distributed values are defined at ELEMENT or NODAL basis, with those being the valid options.

TABLE

Assigns the present distribution to the specified *DISTRIBUTION TABLE

 

 

Sub-Keywords
hmtoggle_plus1*INCLUDE         Include file

Usage

*INCLUDE, INPUT=Input_file

Description

Defines that an external file containing the values for the present distribution should be included into the simulation.

 

Parameters

INPUT

Defines the name of the file to be included (with extension). Note that the included file should be placed in the same folder as the main datafile.

 

 

 

Examples

 

*DISTRIBUTION TABLE, NAME=Elastic_properties

 MODULUS, RATIO

*DISTRIBUTION, NAME=Shale, LOCATION=ELEMENT, TABLE=Elastic_properties

*INCLUDE, INPUT=Elastic_Prop.txt

 

 

1In this example a *DISTRIBUTION TABLE named "Elastic_properties" is defined to set values for Young's Modulus and Poisson's Ratio

2A *DISTRIBUTION named "Shale" with values defined at element centers is defined. This distribution is assigned to *DISTRIBUTION TABLE "Elastic-properties", so *DISTRIBUTION is expected to contain a set rows with comma separatedvalues in the form of:

          Element_number, Young_Modulus, Poisson_Ratio

3The values for *DISTRIBUTION are located in a separate file named "Elastic_prop.txt"

 

 

 

Click to expand/collapseDISTRIBUTION TABLE    Distribution of material properties

Usage

*DISTRIBUTION TABLE,  NAME=Name_ID,  

Description

Defines material properties which will be assigned a spatial distribution via *DISTRIBUTION. This data is equivalent to ParaGeo Spatial_grid input. In addition to the Abaqus input material property labels DENSITY, MODULUS (for Young's Modulus) and RATIO (for Poisson's Ratio) any ParGeo material state variable is valid as an input.

 

Compulsory Parameters

NAME

Defines a name for the distribution table so it can be refereed (required to assign a *DISTRIBUTION).

 

 

Sub-Keywords
hmtoggle_plus1*DISTRIBUTION GROUPS         Include file

Usage

*DISTRIBUTION GROUPS

Description

Defines a list of group names that will be associated with the table. The list should be provided in a new line with names separated by spaces.

 

 

 

Examples

 

*DISTRIBUTION TABLE, NAME=Elastic_properties

 MODULUS, RATIO

*DISTRIBUTION, NAME=Shale, LOCATION=ELEMENT, TABLE=Elastic_properties

*INCLUDE, INPUT=Elastic_Prop.txt

 

 

1In this example a *DISTRIBUTION TABLE named "Elastic_properties" is defined to set values for Young's Modulus and Poisson's Ratio

2A *DISTRIBUTION named "Shale" with values defined at element centers is defined. This distribution is assigned to *DISTRIBUTION TABLE "Elastic-properties", so *DISTRIBUTION is expected to contain a set rows with comma separatedvalues in the form of:

          Element_number, Young_Modulus, Poisson_Ratio

3The values for *DISTRIBUTION are located in a separate file named "Elastic_prop.txt"

 

 

 

Click to expand/collapseGRAVITY    Definition of gravity data

Usage

*GRAVITY,  CONSTANT=9.81,  AMPLITUDE=Amplitude_curve_name

Description

Defines the Gravity data for generation of ParaGeo Gravity_data. This replaces the Abaqus *DLOAD keyword as in ParaGeo the density is computed from porosity and the grain and fluid densities.

 

Optional Parameters

CONSTANT

Defines the gravity acceleration constant (Default: 9.81 m/s2).

AMPLITUDE

Assigns an Amplitude curve (by name) for application of the gravity load. If AMPLITUDE=RAMP is specified the gravity will be ramped up during the first simulation Stage/Step (Default: instantaneous gravity load).

 

 

Examples

 

*GRAVITY, CONSTANT=9.81

 

 

1Gravity load will be ramped during the current simulation stage.

 

 

 

Click to expand/collapseINITIAL CONDITIONS    Initial conditions

Usage

*INITIAL CONDITIONS,  NAME=Name_ID,  TYPE=Prescrived_variable,  INPUT=File_name

Description

Defines initial conditions for any state variable of the problem. Depending on which state variable is being prescribed values are defined at element basis or at nodal basis.  This keyword will result in generation of a ParaGeo Spatial_grid.

 

Compulsory Parameters

NAME

Defines a name with which the generated spatial grid will be identified.

TYPE

Defines which state variable will be prescribed (by name). Valid types are:

- FIELD

- PORE PRESSURE

- POROSITY

- RATIO

- STRESS

- TEMPERATURE

INPUT

Defines the name of the text file (with extension) which contains the values to be prescribed as initial conditions for the selected state variable. The file should be structured as a two columns coma separated values with as many rows as required as follows:

    Element_number, Variable_value

 

 

Examples

 

*INITIAL CONDITIONS, NAME=Void_grid, TYPE=VoidR, INPUT=Void_ratio.txt

 

 

1Void ratio values provided in file "Void_ratio.txt" are going to be used to create a ParaGeo Spatial_grid and use it to establish initial conditions.

 

 

Abaqus Input format

 

** NODEID, VoidR

,  0.42

6,  0.45

7,  0.45

8,  0.45

13,  0.45

14,  0.45

15,  0.45

105,  0.45

126,  0.45

 

 

ParaGeo converted format

 

* Spatial_grid                     NUM=3

! ----------------------------------------

 Name             "1"

 File_name        "VoidR.txt"

 Type             "Mesh_internal"

 Nodal_variables  IDM=1

   "1"

 Node_numbers  IDM=8

    5   6   7  12  13  14  15  16  

 Point_values  IDM=1  JDM=8

   0.450000    

   0.450000    

   0.450000    

   0.450000    

   0.450000    

   0.450000    

   0.450000    

   0.450000