Influence of Phase Shift and Amplitude Ratio on the Principal Stresses and Directions in Multiaxial Fatigue Testing

Abstract

The maximum values of normal and shear stresses are the basic parameters which influence directly the initiation and propagation of multiaxial fatigue cracks.Based on the above, the first part of the paper presents an analysis of principal stresses (normal and shear) in case of symmetrical tension-compression loadings with superimposed phase-shifted symmetrical torsion cycles. The influence of stress amplitude ratio and phase shift on the maximum (normal and shear) stresses and on the directions of the planes along which these act is analyzed and graphically represented using stress hodographs.The second part of the paper highlights the possibility of using the maximum value of the normal or shear stress as base parameter for durability studies under multiaxial fatigue, based on existing experimental data. The mentioned data is correlated with the results of an original experimental program carried out by the authors on 41Cr4 steel and conclusions are formulated with regard to the role of maximum shear stress in life-time calculation.

Fatigue failure modes of rib‐to‐deck joints under the multiaxial stress states caused by various wheel loading characteristics

“…Several studies on multiaxial fatigue have been conducted to understand the cracking behavior. 19,20 Commonly applied multiaxial failure principles in real engineering have been proposed based on the maximum principal stress, 21 equivalent von Mises stress, 22 theory of critical plane, 23 etc. Using the aforementioned approach, Fu et al 24 evaluated the multiaxial fatigue damage in deck and U-rib welds based on multiaxial fatigue loading experiments.…”