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 RectangularHull (MRH) method proposed by the first author. The C–S criterion is a multiaxialhigh-cycle fatigue criterion based on the critical plane approach and takes into account bothshear stress (Mode II) and normal stress (Mode I)mechanisms to evaluate the orientation ofthe critical plane. The fatigue damage parameter used is given by a nonlinear combinationof the equivalent normal stress amplitude,Na,eq, and the shear stress amplitude, Ca, acting onthe critical plane. In the present paper, the shear stress amplitude is evaluated through theMRH method. Some experimental data available in the literature are compared with thetheoretical estimations, concluding that the multiaxial fatigue strength evaluations providedby the C–S criterion are improved when Ca is computed applying theMRHmethod insteadof the Minimum Bounding Circle (MBC) method.