Fatigue analysis of autofrettaged pressure vessels with radial holes

Fatigue analysis has been performed to predict the fatigue life of an autofrettaged pressure vessel containing radial holes subjected to cyclic internal pressure of 200 MPa. Finite element analyses were used to calculate the residual and operating stress distributions of the pressure vessel due to the autofrettage process and pulsating internal pressure, respectively. Numerical stress concentration factors at the hole of the autofrettaged pressure vessel subjected to internal pressure were approximately 3. Fatigue damages, including the mean stress effects, were evaluated using the local stresses and local strains determined from the elastic–plastic finite element analysis. An increase in the amount of overstrain by the autofrettage process moved the fatigue cracking location from the inner radius towards a mid-wall, and extended the fatigue life. Predicted fatigue life of a 50% autofrettaged pressure vessel with radial holes increased by 45%, compared to that of the unautofrettaged pressure vessel. The level of autofrettage did not significantly influence the failure location and fatigue life of the pressure vessel for more than 50% autofrettage level.