Thermo-mechanically loaded steel/aluminum functionally graded spherical containers and pressure vessels

Structures of metal/metal composites like steel/aluminum FGMs allow for significant weight reduction as compared to homogeneous steel devices while maintaining sufficient strength in many applications. Hence, in the present contribution spherical containers and pressure vessels of steel/aluminum power-law graded material under thermo-mechanical load are discussed. Whereas in the majority of previous studies on FGM hollow spheres independent variations of the material parameters were presupposed - leaving the problem of manufacturing such an FGM an open question -, the present investigation is primarily based on the Reuss and Halpin-Tsai homogenization schemes. Their use is suggested by inspecting available test data of a related intermetallic FGM; nevertheless, also the Voigt rule is considered. The temperature dependence of the relevant properties of steel and aluminum (except for Poisson's ratio) is considered, and it is shown that by appropriate functional approximations (semi-)analytical solutions can be found not only for the Voigt but also for the Reuss rule. Both the predicted stress distributions and the elastic limits - based on von Mises' yield criterion - are discussed, and the achievable weight reduction in relation to the strength of the device is assessed.