To model thermal actuators, The Joule Heating and Thermal Expansion Interface is required. This multiphysics interface adds a Solid Mechanics interface, a Heat Transfer in Solids interface, and an Electric Currents interface. Joule heating and the resulting thermal expansion are included as multiphysics coupling nodes under Multiphysics in the model tree. Note that a reference temperature, at which the thermal strains are zero, must be added to the Thermal Expansion node. In the absence of thermal residual stresses this temperature should be specified as the operating temperature.