Discussion on the manuscript entitled “Thermal residual stress in a functionally graded material system” by K. S. Ravichandran, Materials Science and Engineering A, 201(1–2), pp. 269-276

In the article entitled “Thermal residual stress in a functionally graded material system”, a strip element made of a combination of Al₂O₃ ceramic and Ni metal was considered as a functionally graded material to obtain the general expressions for thermal residual stresses. The results showed that the stress distribution changes continuously as the volume fraction of the ceramic varies according to a power function. However, an incorrect term for bending stiffness was used in this expression. In addition, the expression for the residual stress term, which is resulted from the uniform elongation of the strip fibers, should not be used to calculate the reactive bending moment. It must be obtained from the nonuniform distribution of thermal strain across the thickness. In this study, the derivation of the final expression for the thermal residual stress in a functionally graded strip element by the strain suppression method is discussed.