Spreading of Plastic Zones in Functionally Graded Spherical Tanks Subjected to Internal Pressure and Temperature Gradient Combinations

Thermo-Elasto-Plastic analyses of thick-walled spherical tanks made of functionally graded materials are investigated analytically. These tanks are subjected to positive or negative temperature gradient and internal pressure loadings separately or simultaneously. The power law modeling has been used for through-the-thickness variation of mechanical properties. von Mises yield criterion and Elastic-Perfectly-Plastic assumptions are used for describing the material behavior in plastic zones. The patterns of plastic zones spreading for various combinations of internal pressure and positive or negative temperature gradient are investigated. Numerical analyses conducted for the similar problems and excellent agreement with the analytical solutions observed. FG sphere subjected to internal pressure and negative temperature gradient yields at a lower pressure than the FG sphere subjected to internal pressure. Internal pressure and negative temperature gradient combination is the most critical loading combination and positive temperature gradient increases the capacity of FG spherical tank subjected to internal pressure.