Multiaxial fatigue strength of severely notched cast iron specimens

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

“…Common to all cited studies is the finding, that the fatigue life of NCI is governed by the size of a single graphite particle or casting defect, resp., from where the fatigue crack initiates. Recently, the field of multi-axial fatigue of NCI also attained attraction [16,35].…”

Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

“…The idea of a control volume size dependent on the loading mode has been proposed for the first time in [4] dealing with the multiaxial fatigue strength assessment of notched specimens made of 39NiCrMo3 steel, then it has been successfully applied also for the fatigue strength assessment of notched components made of AISI 416 [25] and cast iron EN-GJS400 [26] subjected to combined tension and torsional loading. Once the size of the control volume is properly defined, the averaged SED can be evaluated directly from the FE results, W  , by summation of the strain-energies WFEM,i calculated for each i-th finite element belonging to the control volume V (or area A in two-dimensional problems, as shown in Fig.…”

Joined application of a multiaxial critical plane criterion and a strain energy density criterion in low-cycle fatigue

“…The fatigue life assessment is carried out at a verification point (point P ), which is distant r from the notch tip. Such a distance r , measured along the notch bisector line, is a function of both the biaxiality ratio  and the control volume radii provided by the SED criterion [8,9]:…”

“…Such a criterion is an extension of the critical plane-based multiaxial fatigue criterion proposed by Carpinteri et al for smooth specimens [6,7] to the case of notched ones. The above extension is formulated by implementing the concept of the control volume, related to the Strain Energy Density (SED) criterion proposed by Lazzarin et al [8,9]. More precisely, the fatigue life assessment is performed by taking into account the strain state at a material point (named verification point) located at a certain distance from the notch tip, depending such a distance on both the biaxiality ratio  (remote shear stress amplitude over remote normal stress amplitude) and the control volume radii under loading conditions of Mode I and Mode III.…”