An alternative definition of the shear stress amplitude based on the Maximum Rectangular Hull method and application to the C-S (Carpinteri-Spagnoli) criterion

In the present paper, the fatigue strength estimation capabilities of the modified C-S (Carpinteri-Spagnoli) criterion are improved by employing the Maximum Rectangular Hull (MRH) method proposed by the first author. The C-S criterion is a multiaxial high-cycle fatigue criterion based on the critical plane approach and takes into account both shear stress (Mode II) and normal stress (Mode I) mechanisms to evaluate the orientation of the critical plane. The fatigue damage parameter used is given by a nonlinear combination of the equivalent normal stress amplitude, Na,eq, and the shear stress amplitude, Ca, acting on the critical plane. In the present paper, the shear stress amplitude is evaluated through the MRH method. Some experimental data available in the literature are compared with the theoretical estimations, concluding that the multiaxial fatigue strength evaluations provided by the C-S criterion are improved when Ca is computed applying the MRH method instead of the Minimum Bounding Circle (MBC) method.