You can create a surface charge load to apply a distributed electric charge to a surface in a piezoelectric analysis.
To create or edit a surface charge:
Display the surface charge load editor using one of the following methods:
To create a new surface charge load, follow the procedure outlined in “Creating loads,” Section 16.8.1 (Category: Electrical/Magnetic; Types for Selected Step: Surface charge).
To edit an existing surface charge load using menus or managers, see “Editing step-dependent objects,” Section 3.4.13. To edit the region to which the load is applied, see “Editing the region to which a prescribed condition is applied,” Section 16.8.4.
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 a load that is uniform over the surface.
Select an analytical field to define a spatially varying load. Only analytical fields that are valid for this load type are displayed in the selection list. Alternatively, you can click 
to create a new analytical field. (See Chapter 58, “The Analytical Field toolset,” for more information.)
In the Magnitude field, enter the charge density (units CL–2).
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click 
to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Note: The amplitude field appears only if amplitudes are valid for the type of perturbation step in which you are creating the load. For more information, see “Linear perturbation analysis steps,” in “General and linear perturbation procedures,” Section 6.1.3 of the Abaqus Analysis User's Guide.
Click OK to save your data and to exit the editor.
