Biaxial Strain Accumulation in Mechanical Ratcheting Under Varied Cyclic Stress Conditions

Abstract

This paper describes the experimental results of mechanical ratcheting under biaxially varied stress conditions. The experiments were conducted by subjecting thin-walled tubular specimens of a carbon steel to a combination of a cyclic axial load and internal pressure at room temperature. The effect of the simultaneous variation of maximum effective stress, stress ratio and superposed stress with an increase in the number of cycles on the biaxial strain accumulation is discussed. The strain history dependence on the orientation of strain accumulation was observed in the ratcheting under varied superposed stress conditions. The results of numerical simulations obtained by the constitutive equation, previously presented by the author and his co-workers, agree comparatively well with the corresponding experimental results, except during rapid variation of a superposed stress.