2. 1 THERMAL STRESSES Temperature change causes thermal strain Constraints cause thermal stresses Thermo-elastic stress-strain relationship (a) at T = T ref (b) at T = T ref +  T No stress, no strain No stress, thermal strain Thermal stress, no strain L L LL Thermal expansion coefficient

3. 2 THERMAL STRESSES in FE Force-displacement relation Finite element equation For plane truss, transform to the global coord. Thermal force vector

4. 3 SUPERPOSITION APPROACH.

5. 4 TWO-BAR TRUSS EXAMPLE Element 1 is heated Will it be in compression? Tension? No stress? What about Element 2? Thermal load Solve!