Residual Stresses and Lifetimes of Tubes Subjected to Shrink Fit Prior to Autofrettage

There is increasing interest in the use of compound cylinders that combine shrink fit and autofrettage, taking account of Bauschinger effect. Previous work has analyzed material removal from a plain, autofrettaged cylinder and the application of an external pressure or shrink to a previously autofrettaged plain tube. In this paper a different design philosophy is examined, namely the shrink fitting of two tubes prior to autofrettage. Such a process is shown to be beneficial in inhibiting loss of near-bore compressive residual hoop stress due to Bauschinger effect and thereby increasing calculated fatigue lifetime. These effects are described in detail for a specific geometry, and summary data suitable for use by designers are presented for a large range of configurations.