Defining Materials and Media Types

Materials can be defined in CUBIT and assigned to element blocks. If an element block is exported without a material assigned to it, a default material (with properties for common steel) will be exported for it.

Create Material [id] [Name <'name'>] [Elastic_modulus <value>] [Poisson_ratio <value>] [Shear_modulus <value>] [Density <value>] [Specific_heat <value>] [Conductivity <value>] [User constants <value ...>] [DepVar <value>]

Modify Material <id_list|'name'|all> [Name <'name'>] [Elastic_modulus <value>] [Poisson_ratio <value>] [Shear_modulus <value>] [Density <value>] [Specific_heat <value>] [Conductivity <value>] [User constants <value ...>] [DepVar <value>]

Create Media [id] [Name <'name'>] [Fluid|Porous|Solid]

Modify Media <id_list|'name'|all> [Name <'name'>] [Fluid|Porous|Solid]

Materials can be created with any number of the following material properties:

• Elastic modulus
• Poisson Ratio
• Density
• Specific Heat
• Conductivity
• Shear Modulus (must satisfy E = 2G(1+v) )
• User Constants
• DepVar (Only written to Abaqus file)

Media types include:

• Fluid
• Porous
• Solid

Any properties that are not initialized by the user will have a default value of 0.

Materials and media types can be listed and deleted using the following commands:

List Material <id_list|'name'|all>

Delete material <id_list|'name'|all>

List Media <id_list|'name'|all>

Delete Media <id_list|'name'|all>

Materials and media can be added to an existing block using the following command:

Block <id> Material <id|'name'>

Block <id> Media <id|'name'>

Custom Material Commands

The Cubit SDK allows custom material properties to be defined using the MaterialInterface. The following versions of the material commands allow users to create materials with custom properties that have already been defined using the SDK.

Create {material|media} 'material_name' property_group 'group_name' [id <requested_id>] [description 'string']

Modify {material|media} 'material_name' [property_group 'group_name'] [id <requested_id>] [description 'string'] [rename 'new_name']
[scalar_properties ('property_name' <property_value>)...]
[vector_property 'property_name' <val1> <val2>...]
[matrix_property 'property_name' <val1> <val2>...]
[clear properties 'property_name1' 'property_name2'...]

A scalar property has a single value associated with it. The scalar properties defined by Cubit are:

• "MODULUS" (The modulus of elasticity)
• "SHEAR_MODULUS"
• "POISSON" (Poisson's ratio)
• "DENSITY"
• "SPECIFIC_HEAT"
• "CONDUCTIVITY" (Thermal conductivity, not electrical)
• "THERMAL_EXPANSION"
• "YIELD_STRENGTH"
• "ULTIMATE_STRENGTH"
• "ULTIMATE_STRAIN"
• "DEPVAR" (Property required for Abaqus export)
• "CFD_MEDIA_TYPE" (0 = fluid; 1 = porous; 2 = solid)

Vector properties are given in the command as a list of values. The vector properties defined in Cubit are:

• "USER_CONSTANTS" (User-defined material constants)

Matrix properties are also given as a list of values. The number of columns in the matrix is defined by the specific property, and Cubit automatically divides the given values into rows and columns based on the column count. For example, if a matrix property has 2 columns, the value list "2 33.1 3 18.9" is interpreted as the matrix:

• "ELASTIC_MODULUS_VS_TEMPERATURE" (2 columns)
• "POISSONS_RATIO_VS_TEMPERATURE" (2 columns)
• "DENSITY_VS_TEMPERATURE" (2 columns)
• "YIELD_STRESS_VS_STRAIN_VS_TEMPERATURE" (3 columns)
• "SPECIFIC_HEAT_VS_TEMPERATURE" (2 columns)
• "CONDUCTIVITY_VS_TEMPERATURE" (2 columns)

A property group is a collection of material properties. Its main purpose is to help define what properties a material should have, even if a value is not given for the property. Cubit defines the following property groups:

• "CUBIT-FEA" (generic FEA material)
• "CUBIT-ABAQUS" (material specific to Abaqus export)
• "CUBIT-CFD" (generic CFD media)

Table 1. Property groups defined in CUBIT