Consideration of damage in the analysis of autofrettage of thick-walled pressure vessels

In this study, the influence of material damage and the Bauschinger effect on the autofrettage of thick-walled pressure vessels is investigated. Constitutive equations for the elasto-plastic deformation and damage processes are presented. Boundary value problems for a thick-walled cylinder and for a thick-walled sphere of constant thickness are formulated. Computations are preformed to find the optimum autofrettage pressure, for which the equivalent stresses in the vessel take the minimum value under process conditions. Furthermore, residual stress fields after the autofrettage are analyzed. The results show that the Bauschinger effect and damage lead to essential reduction of favorable residual stresses.