Effects of Material Gradients on Onset of Yield in FGM Rotating Thick Cylindrical Shells

In this paper, a closed-form solution to determine location of yield in rotating thick-walled cylindrical shells made of functionally graded materials (FGMs) using both Tresca's and von Mises yield criteria is presented. The cylindrical shell is subjected to uniform internal and external pressure. The material properties are assumed to vary according to power law functions and the Poisson's ratio is assumed to be constant. Moreover, the plane strain condition is used to drive expressions for distributions of stresses and radial displacement. In the present work, rotation, internal and external pressure and variation of material properties are considered simultaneously. To the best of authors' knowledge, in previous researches in which onset of yield is investigated, variation of material density is ignored, while density is not constant in FGM rotating thick cylindrical shells. Our results show that the density variation has a significant effect on the stress distributions. Our research has also tried to explain the effect of different Poisson's ratio on the value of the critical material parameter.