Hygroscopic Swelling
Hygroscopic swelling is an internal strain caused by changes in moisture content. This strain can be written as
where βh is the coefficient of hygroscopic swelling, Μm is the molar mass, cmo is the moisture concentration, and cmo,ref is the strain-free reference concentration.
You can provide a concentration with a through-thickness variation by explicitly or implicitly use expressions containing the extra dimension coordinate as described in Using the Extra Dimension Coordinates.
Shell Properties
Select the layer or layers for which this swelling strain contribution is to be added.
Table 6-13: Layer Selections; Hygroscopic Swelling.
Selection
Use All Layers
Selection of Individual Layers
Boundary
Same as parent selection when the node is added.
When Use all layers is not selected.
Only a subset of the layers selected in the parent can be selected.
If the swelling properties differ between layers, you will need to add several Hygroscopic Swelling nodes with different layer selections. If only the material data values differ, you can use a single Hygroscopic Swelling node with From material. The data for each layer is then received from global Layered Material nodes.
If the same layer is selected in two Hygroscopic Swelling nodes being active on the same boundary, the second definition will override the previous.
Hygroscopic strains are proportional to the concentration, while structural strains are computed from the gradient of the displacement field. It is good practice to match the discretization order of hygroscopic and structural strains.
When adding a Hygroscopic Swelling subnode, and the concentration field is computed by another physics interface; use a discretization one order lower for the concentration field than what is used for the displacement field.
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All other settings for the Hygroscopic Swelling node are described in the documentation for Hygroscopic Swelling in the Solid Mechanics interface.
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For a general description of layer and interface selections, see The Shell Properties and Interface Selection Sections.
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You can provide parameters for the swelling with a through-thickness variation by explicitly or implicitly using expressions containing the extra dimension coordinate as described in Using the Extra Dimension Coordinates.
Location in User Interface
Context Menus
Layered Shell>Linear Elastic Material>Hygroscopic Swelling
Layered Shell>Hyperelastic Material>Hygroscopic Swelling
Ribbon
Physics tab with Linear Elastic Material or Hyperelastic Material node selected in the model tree:
Attributes>Hygroscopic Swelling