A material assignment field is used to specify the geometric composition of different materials in the initial state of an Eulerian part instance. The available materials that can be assigned depend on the material instances defined in the Eulerian section assigned to the part. For a general overview of material assignments for Eulerian parts, see “Assigning materials to Eulerian part instances,” Section 28.4.
Each Eulerian part instance in a model can have only one material assignment field applied to it. Conversely, a material assignment field can be applied to only one Eulerian part instance; if you have multiple Eulerian part instances in your model, you must create a material assignment field for each instance.
Materials are assigned by selecting a region of the Eulerian part instance, then specifying the material instances that are present in that region. Each material instance is assigned a percentage indicating the volume fraction occupied by the material instance within the selected region. If the material instance percentages within a region do not add up to 100%, the remaining volume fraction in the region is occupied by a void with no material properties. A void is also assigned by default to any regions within the part instance for which a material assignment is not explicitly specified. For a detailed discussion of how Abaqus interprets material volume fractions, refer to “Eulerian analysis,” Section 14.1.1 of the Abaqus Analysis User's Guide.
To create or edit a material assignment field:
Display the material assignment field editor using one of the following methods:
To create a new material assignment field, follow the procedure outlined in “Creating predefined fields,” Section 16.8.3 (Category: Other; Types for Selected Step: Material assignment). You can create a material assignment field only during the initial step.
To edit an existing material assignment field using menus or managers, see “Editing step-dependent objects,” Section 3.4.13. You can modify a material assignment field only during the initial step, and you cannot edit the region to which the material assignment field is applied.
Specify the method you are using to define volume fractions for each material instance:
Choose Uniform to define volume fractions that are uniform across each region.
Choose Discrete fields to define the volume fractions using discrete fields. Discrete fields can be used to define volume fractions that are spatially varying across a region.
Select a region for the material assignment. The region must be contained within the part instance that was selected in Step 1. If the Eulerian part consists of a single cell (there are no interior partitions), Abaqus/CAE automatically selects the whole part.
Click mouse button 3 in the Region column of the Volume Fractions table, and select Edit Region from the menu that appears. Alternatively, you can double-click mouse button 1 in the Region column.
Select cells in the part instance using one of the following methods:
Select and unselect cells in the viewport. When you have finished selecting the cells, click mouse button 2. (For more information, see Chapter 6, “Selecting objects within the viewport.”)
To select from a list of existing sets, click Sets on the right side of the prompt area, select the set of interest in the Region Selection dialog box, and click Continue.
Note: The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Sets on the right side of the prompt area.
The remaining columns in the Volume Fractions table correspond to the material instances in the Eulerian section. The material instance name is appended to the part instance name in the column headings (for example, a column labeled Bottle-1.Water corresponds to a material instance named Water in a part instance named Bottle-1). If you are defining uniform volume fractions, a Void column also appears; you cannot edit values in the Void column. In the columns corresponding to each material instance, enter the appropriate volume fraction for the region:
If you are defining uniform volume fractions, enter the volume fraction for each material instance as a percentage in decimal form. For example, enter 0.45 for a volume fraction of 45%. Values greater than 1 are automatically reset to 1. To assign all material instances equally to a region, click mouse button 3 anywhere in the Volume Fractions table, and select Equalize Rows from the menu that appears.
Note: As you enter material volume fractions, Abaqus/CAE automatically adjusts the value in the Void column so that all values in the table row sum to one. If the sum of the entered values is greater than one, Abaqus/CAE automatically sets Void to zero and normalizes the remaining values so that they sum to one.
If you are defining the volume fractions using discrete fields, click in the material instance columns; then click the arrow that appears and select a name from the list of available discrete fields. If the discrete field has not been defined, click mouse button 3 anywhere in the Volume Fractions table, and select Create Discrete Field from the menu that appears to access the Discrete Field toolset (see “Creating discrete fields,” Section 63.2). Volume fractions in the discrete field definition should be specified as percentages in decimal form; for example, enter 0.45 for a volume fraction of 45%. Data in the discrete field definition for elements that are not within the selected region are ignored.
Warning: Because discrete fields are mesh-dependent, subsequent modifications to the Eulerian part mesh will invalidate a material assignment based on discrete fields.
To clear all material volume fraction values from a row, click mouse button 3 anywhere in the row, and select Clear Rows from the menu that appears.
To define material volume fractions in another region of the part instance, click mouse button 3 in the Volume Fractions table, and select Add Row from the menu that appears.
Abaqus/CAE adds a new row to the Volume Fractions table. Repeat the above steps to define a new region and its associated material volume fractions.
Once material instances have been appropriately assigned to all regions of the part instance, click OK to save your data and to exit the material assignment field editor. If material instances are not assigned to some regions of the part instance, those regions are initially assigned a void with no material properties.
