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.

When using Common model input, you can see or modify the value of the volume reference temperature by clicking the Go To Source button (). This will move you to the Common Model Inputs node under Global Definitions in the Model Builder. The default value is room temperature, 293.15 K.

If you want to create a model input value which is local to your current selection, click the Create Model Input button . This will create a new Model Input node under Definitions in the current component, having the same selection as the current Thermal Expansion node.

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 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. Use 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:
Attributes>Thermal Expansion