You can define density as a function of temperature and field variables. For acoustic, heat transfer, coupled temperature-displacement, and coupled thermal-electrical elements the density is continually updated to the value corresponding to the current temperature and field variables. However, for all other elements density is a function of the initial values of temperature and field variables and changes in volume only. Abaqus does not update density values if temperatures and field variables change during the analysis.
See “Density,” Section 21.2.1 of the Abaqus Analysis User's Guide, for more information.
To specify density:
From the menu bar in the Edit Material dialog box, select General
Density.
(For information on displaying the Edit Material dialog box, see “Creating or editing a material,” Section 12.7.1.)
Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:
Select Uniform to define density that is uniformly distributed throughout the material.
Select an analytical field, labeled with an (A), or a discrete field, labeled with a (D), to define a spatially varying density. Only analytical fields and discrete fields that are valid for density are available in the selection list. See Chapter 58, “The Analytical Field toolset,” and Chapter 63, “The Discrete Field toolset,” for more information.
Alternatively, you can click 
to create a new discrete field.
Toggle on Use temperature-dependent data to define density as a function of temperature.
A column labeled Temp appears in the Data table.
Click the arrows to the right of the Number of field variables field to increase or decrease the number of field variables on which the density depends.
Enter the following data in the Data table:
Mass Density
Mass density. (Units of ML–3.)
Temp
Temperature.
Field n
Predefined field variables.
Click OK to close the Edit Material dialog box. Alternatively, you can select another material behavior to define from the menus in the Edit Material dialog box (see “Browsing and modifying material behaviors,” Section 12.7.2, for more information).