Effect of autofrettage in the thick-walled cylinder with a radial cross-bore

The effect of autofrettage on the stress level in thick-walled cylinders with a radial cross-bore is investigated by applying inelastic FEA with cyclic pressure loading. A macro is created in ANSYS to calculate the equivalent alternating stress intensity, S-eq, based on the ASME Boiler and Pressure Vessel Code. The value Of S-eq is used to evaluate the fatigue life of the vessel. For a specific cyclic load level, a distinct optimum autofrettage pressure is identified by plotting autofrettage pressure against the number of cycles from design fatigue data. The fatigue life of the autofrettaged vessel with such an optimum pressure is significantly increased compared with the case where no autofrettage is used.