LOW-CYCLE FATIGUE LIFE PREDICTIONS FOR HOLLOW TUBES WITH AXIALLY LOADED AXISYMMETRICAL INTERNAL PROJECTIONS

The finite element method has been used to study the monotonic and cyclic elastic-plastic stress and strain characteristics of hollow tubes with axisymmetric internal projections subjected to monotonic and repeated axial loading. This paper compares finite element strain predictions with values estimated using simple notch stress-strain conversion equations for two geometries and a range of nominal stresses. From this study, an intermediate equation (m = 0.5) is suggested for low cycle fatigue life predictions. The results have been normalized with respect to material properties so that they can be applied to geometrically similar components made from other materials which can be represented by the same material models.