When a solid material is subjected to a temperature differential, the structure of the material changes and causes a volumetric expansion. This deformation can induce stresses in the material. Thermal stresses must often be accounted for and avoided, for example in the construction of railways, roads, or copper interconnects used in microelectronic devices.

Modeling thermal expansion involves a coupling between heat transfer and structural mechanics that can, in many cases, be solved sequentially. In some cases, the material's elasticity and thermal expansion coefficients are heavily temperature dependent, and
the temperature and displacement fields must be coupled simultaneously.

Simulation of a Microrobot

This example shows the model of a silicon microrobot leg. An electric current flowing through the leg generates heat. Because of thermal expansion and differing thermal expansion coefficients of the leg's materials, a bending action is induced.