Thermal Expansion (for Materials)
Use the Thermal Expansion subnode to add an internal thermal strain caused by changes in temperature.
The Thermal Expansion subnode is only available with some COMSOL products (see https://www.comsol.com/products/specifications/).
Shell Properties

This section is only present when Thermal Expansion is used as a subnode to:
Linear Elastic Material in the Layered Shell interface. See the documentation for the Thermal Expansion (for Materials) node in the Layered Shell chapter.
Layered Linear Elastic Material in the Membrane interface. See the documentation for the Thermal Expansion (for Materials) node in the Membrane chapter.
This section is only present in the in the Layered Shell interface, where it is described in the documentation for the Thermal Expansion (for Materials) node.
Model Inputs
The Volume reference temperature Tref is the temperature at which there are no thermal strains. As a default, the value is obtained from a Common model input. You can also select User defined to enter a value or expression for the temperature locally.
The Temperature T is by default obtained from a Common model input. You can also select an existing temperature variable from a heat transfer interface (for example, Temperature (ht/sol1)), if any temperature variables exist. or manually enter a value or expression by selecting User defined.
When adding a Thermal Expansion subnode in a Layered Shell or Membrane interface, and the temperature field is computed by another physics interface (often the Heat Transfer in Shells interface); use a discretization one order lower for the temperature field than what is used for the displacement field.
Default Model Inputs and Model Input in the COMSOL Multiphysics Reference Manual.
Thermal Expansion Properties
Select an Input type to select how the thermal strain is specified. The default is Secant coefficient of thermal expansion, in which case the thermal strain is given by
where α is the secant coefficient of thermal expansion. α can be temperature dependent.
When Input type is Tangent coefficient of thermal expansion, the thermal strain is given by
where αt is the tangential coefficient of thermal expansion.
When Input type is Thermal strain, enter the thermal strain dL as function of temperature explicitly.
In all three cases, the default is to take values From material. When entering data as User defined, select Isotropic, Diagonal, or Symmetric to enter one or more components for a general coefficient of the thermal expansion tensor or the thermal strain tensor. When a nonisotropic input is used, the axis orientations are given by the coordinate system selection in the parent node.
A heat source term will be created by this node. It can be accessed from a Thermoelastic Damping node in a heat transfer interface in order to incorporate the reversed effect that heat is produced by changes in stress. The heat source term is only present when Structural Transient Behavior is set to Include inertial terms.
Thermal Stresses in a Layered Plate: Application Library path
Structural_Mechanics_Module/Thermal-Structure_Interaction/layered_plate
MEMS_Module/Actuators/layered_plate
Location in User Interface
Context Menus
Ribbon
Physics tab with Linear Elastic Material, Hyperelastic Material, Nonlinear Elastic Material, Elastoplastic Soil Material, Piezoelectric Material, or Magnetostrictive Material node selected in the model tree: