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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 LL Thermal expansion coefficient

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

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3 SUPERPOSITION APPROACH.

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