Strain-Based Damage Models to evaluate Fatigue Life of Steel Alloys Under Uniaxial Variable Loading

The intention of this study is to estimate fatigue damage and life of different steel alloys under uniaxialvariable amplitude loading conditions based on three critical plane strain-based models. Fatemi-Socie (FS) damagemodel evaluates fatigue lives of the samples based on the shear strain and normal stress acting on critical plane wheremaximum shear strain takes place. The assessment of fatigue damage by means of the Macha model is based on linearsummation of shear and normal strain whereas Carpinteri-Spagnoli (CS) model involves both axial and shear strain inthe nonlinear form on critical plane. Uniaxial variable loading spectra is counted and partitioned into the number ofreversals by means of the rainflow cycle counting method. The largest stress and strain Mohr’s circles over the countedreversals are constructed to determine the maximum shear strain magnitude and corresponding stress to evaluatedamage of each reversal. The total damage over entire loading history is then calculated based on the linear damagerule of Miner. The predicted lives based on three damage models are compared with those of reported experimentaldata. Fatigue life data evaluated by Macha and CS criteria with different descriptions show a closer agreement to theexperimentally obtained fatigue lives of steel samples.

کلیدواژه ها:

Variable loading ، critical plane ، cycle counting ، Mohr’s circle ، fatigue life prediction