Determination of residual stress distributions in autofrettaged tubing: A discussion

Abstract

There is a long-standing interest in developing a capability to predict the distribution of residual stresses in thick-wall tubes after internal pressurization—autofrettage. Since autofrettage involves partial or full plastic deformation of the tube, any computation of stress under pressure and, hence of the post-pressurization residual stresses, depends upon the assumed yield criterion. The latter may or may not include the material's strain-hardening and/or strain-softening capabilities. The most commonly used criteria are those named after Tresca and Mises. In the absence of exact solutions for plastic deformations, simplifying assumptions concerning the material's behavior have been made for the development of workable solutions, sometimes with the knowledge that certain physical principles are being violated. Many suggested solutions to the problem of autofrettage assume that Tresca's yield criterion prevails. Recent attempts to treat a ‘modified Tresca's yield criterion’ as Mises' yield criterion and/or attempts to add strain-hardening and/or strain-softening (Bauschinger effect) to Tresca's yield criterion are being questioned here.