where βh is the coefficient of hygroscopic swelling,
cmo is the moisture concentration, and
cmo,ref is the strain-free reference concentration. It is possible to model bending due to a concentration gradient in the transverse directions of the beam. The concentration is then assumed to vary linearly through the thickness.
From the Concentration c list, select an existing concentration variable from another physics interface, if any concentration variables exist. For
User defined enter a value or expression for the concentration. This is the centerline concentration of the beam, controlling the axial part of the hygroscopic swelling.
The unit for the input depends on the setting of Concentration type in the
Hygroscopic Swelling Properties section. Only concentration variables having the chosen physical dimension are available in the
Concentration list.
In the Concentration type list, select
Molar concentration (the default) or
Mass concentration, depending on the units used for the concentration.
Enter a Strain reference concentration cref. This is the concentration at which there are no strains due to hygroscopic swelling.
If Molar concentration is selected as
Concentration type, also enter the
Molar mass of the fluid,
Mm. The default value is 0.018 kg/mol, which is the molar mass of water.
The default Coefficient of hygroscopic swelling βh uses values
From material. For
User defined select
Isotropic (the default),
Diagonal, or
Symmetric to enter one or more components for a general coefficient of hygroscopic swelling tensor
βh. The default value for the
User defined case is
1.5e-4 m
3/kg.
Enter the Concentration gradient in local y direction cgy (in 2D and 3D) and in the
Concentration gradient in local z direction cgz (in 3D), which affects the hygroscopic bending. If beam cross-section dimensions have been defined at
Bending stress evaluation points —
From section heights, these could be used in an expression containing the concentration difference.
Physics tab with Linear Elastic Material node selected in the model tree:
