Investigation the Creep Behavior Affected by FGM Constant in Pressure Vessels under Thermo-Mechanical Loads

Temperature and pressure dependent creep stress analysis of a thick-walled FGM spherical pressure vessel under thermo-mechanical loadings have been studied. A method based on Taylor Series of creeping strains rate is employed for solving the governing equation by model updating method and considering the nonlinearity of the creeping behavior. The results obtained for various material constants through wall-thickness of the vessel are compared and reveal that for vessels with high wall thickness and heterogeneity constants, although the material gradient constants has a great influence on the distribution of elastic stress and strain, it has no effect on the creep steady-state stress distribution. Also, this method can be generalized for other creeping problems of symmetric FGM structures, due to the compatibility of the both numerical and analytical methods.