You can create a table while defining a boundary condition by selecting from the Magnitude menu on the Details pane. Mechanical automatically adds a Tables object (if one does not already exist) and creates an empty table with the following variables:
The independent variable Time.
A dependent variable that is relevant to the boundary condition. For example, if you add a table while defining a pressure load, Pressure is the dependent variable.
See Enter and Edit Data in a Table for instructions on how to add data to the new table. For more information on how to use tables to define loads on boundary conditions, see Specifying Loads with Tables.