Residual stresses in autofrettaged functionally graded pressurized thick cylinders

A popular process in the high-pressure vessel industry is the use of autofrettage to enhance the performance of thick-walled cylinders subjected to high internal pressure. This work focuses on nonlinear behavior of pressurized thick-walled cylinders made of functionally graded materials. The stress distributions in these cylinders are determined analytically using the Von-Mises yield criterion considering an elastic perfectly plastic material and taking into account the Bauschinger effect during unloading. Increasing the strength-to-weight ratio and extending the fatigue life of thick-walled cylinders are their two primary design goals. These goals can be met by generating a residual stress field in the cylinder wall before usage. The gradient index was made to vary from -2 to 2 and different cylinder aspect ratio ranging from 1 up to 3 are considered. Analytical and numerical methods are both utilized to examine how residual stresses affect load-bearing capability.