A stress-strain history theory is developed for the entire life of solid cylinders subjected to reversals of torque under low-endurance fatigue conditions. Thin tubes and solid cylinders of a hot rolled mild steel are found to have identical stress range versus strain range relationships. However, fatigue behaviour is dependent on the stress field surrounding the crack initiation zone and hence the geometry of specimens has a most important effect in high strain fatigue processes. Cold drawn mild steel tubes that have an internal to outside diameter ratio in excess of 0.5 have reduced lives because of the absence of the constraining, less highly stressed core.

The major difficulty in applying high strain fatigue data to technological problems lies not in the fatigue aspect per se but in the prediction of the cyclic strain amplitudes. In this paper they are postulated for the cyclic bending of beams using large deflection theory and taking into account the changing stress-strain relationships which occur as cycling progresses. These theories have been tested using beams of rectangular cross section made of three different materials: mild steel, stainless steel, and an aluminum alloy. Good correlation has verified their applicability.