Author(s)

C. Harrison, A.S. Manning and S.J. Harvey

Abstract

If a component is subjected to a cyclic plastic strain superimposed upon a constant load in an orthogonal direction there is an irreversible plastic ratchet strain, in the direction of the constant load, for each cycle of plastic strain. A typical example of this behaviour is a cylinder subjected to cyclic plastic axial loading superimposed upon an applied hoop stress. The effect of ratchetting for successive cycles is cumulative and may cause a component to fail, and is of concern in the design of pressure vessels and piping runs within the power generation industry. The Design Code [1] specifies basic stress intensity limits based upon static collapse, rather than incremental collapse resulting from high-strain low-cycle fatigue conditions. It has been suggested [2] that the code is over conse

Keywords