To include the effects of hygroscopic swelling, the Hygroscopic Swelling subnode is available from the context menu (right-click the parent node, Linear Elastic Material node, for example) or from the Physics toolbar, Attributes menu. Enter a constant concentration or an analytic expression that can depend on the coordinates or dependent variables. For beams, plates, and shells it is also possible to specify bending swelling loads caused by concentration gradient in the transverse direction. More details are available in the descriptions for each physics interface.

When a separate physics interface is used to model the moisture diffusion in the material, the entry for the concentration is the dependent variable for the concentration from that physics interface, typically c. In most cases, possible concentration variables from other physics interfaces can be directly selected from a list.