Prismatic hull: A new measure of shear stress amplitude in multiaxial high cycle fatigue

The largest rectangular prismatic hull enclosing the deviatoric stress history is proposed as a measure of shear stress amplitude in multiaxial high cycle fatigue. The axes of the prismatic hull represent the amplitudes of the stress history along its directions, allowing a proper characterization of non-proportional loadings. The resulting multiaxial fatigue endurance criterion, simple to implement and very cost effective from the computational point of view, provides predictions which are in sound agreement with a wide variety of available fatigue experiments involving combined normal and shear stresses, with harmonic and non-harmonic, synchronous and asynchronous waveforms.