Residual stress analysis in strain-hardened annular disks with arbitrary thickness and density under rotational autofrettage

Autofrettage is a cold metal forming process that aims to improve the load-bearing capacity and delay the crack initiation for thick-walled annular disks/cylinders. The current study presents numerical solution of stress distribution during the loading and unloading stage subjected to rotational autofrettage for uniform and non-uniform annular disks. The analysis assumed the plane stress condition, von Mises yield criterion, and polynomial strain hardening behavior. The stress distribution during loading and after unloading has been demonstrated for a typical SS304 uniform disk and later validated the results using a 2D FEM model in ABAQUS software. A comparative analysis has been conducted to understand the pressure-bearing capacity in second-stage loading between numerical solutions based on the von Mises yield criterion incorporating perfectly plastic hardening behavior and the proposed model. Furthermore, the stress distribution has been evaluated for non-uniform thickness and density rotating annular disks, and numerical experimentation has been conducted to underscore the importance of profile-specific strategies to induce desired beneficial compressive residual stress in the inner region of the disk.