Dynamic Analysis of Autofrettage under Transient Loading in FG Thick-Walled Cylinder with Work Hardening Behavior Using Numerical Method

In the present article, a numerical procedure is developed for dynamic analysis of residual stress in the process of autofrettage under working pressure. The governing dynamical equations are discretized using finite difference method. Toward This end, differential equations are integrated and by employing divergence theorem surface integrals are converted to boundary integrals. Finally, the C/C++ numerical programming is prepared using the explicit Lagrangian formalism. The effect of transient loading and geometry is investigated in the process of autofrettage on functionally graded cylinders considering elasto-plastic stress wave propagation. The residual stress resulting from internal pressure changes structural load bearing capacity of the cylinder. For functionally graded materials whose material properties change continuously, dynamical analysis yield results which are entirely different as compared with their static counterparts due to the change in wave length and acoustic impedance. In the static analysis the dimensionless forms of equations can be developed from the onset, while in the dynamic analysis the physical dimensions gain importance due to inherent properties of the stress waves.