Thermal Stresses In Composite Or Compound Bars:

In previous Section on stepped bars, we have seen one kind of composite bar where bars of different materials are serially joined. In this section, we will consider another kind of compound bar, a bar built from two different materials rigidly joined together as illustrated in Figure (a), or two bars of different materials in spite of equal length held among two rigid plates as illustrated in Figure (b).

(a)                                                                                  (b)

Figure

If the specific bars were free to expand (or contract) because of temperature changes, they would do so to different amounts (for the similar change in temperature), as illustrated in Figures (a) & (b), because of the difference in the coefficients of linear expansion of the two materials.