Use the Thermal Expansion subnode to add an internal thermal strain caused by changes in temperature.

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.

From the Temperature T list, select an existing temperature variable from another physics interface, if any such temperature variables exist, or select User defined to enter a value or expression for the temperature.

Select an Input type to specify how the thermal strain is defined. 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, which can be temperature dependent. As a default, the Common model input. You can also select User defined to enter a value or expression.

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. Select User defined to enter an expression for the coefficient of thermal expansion or thermal strain.

Physics tab with Linear Elastic Material node selected in the model tree: