Multiaxial fatigue life modeling based on stress gradient and additional hardening
Considering the influence of non-uniform stress field and non-proportional additional hardening on the fatigue damage evolution process,a fatigue life prediction model for multiaxial notched specimens is established to solve the problem that the stress gradient and additional hardening effect are not considered in Manson-Coffin equation.Firstly,considering the physical mechanism of crack initiation and propaga-tion,the location of the critical plane is determined by using the maximum shear strain amplitude as the damage parameter based on the coordinate transformation principle and the critical plane theory.Secondly,the normal stress and shear stress on the critical plane are normalized,and the new equivalent stress gradi-ent factor is determined considering the multiaxial stress concentration factor and stress gradient influence index.Meanwhile,taking into account the influence of phase difference,path non-proportion,and materi-al non-proportion on fatigue life,a new non-proportional additional hardening factor is proposed.Finally,a new multiaxial fatigue life prediction model is proposed based on the Manson-Coffin equation.The pre-diction life of the proposed model,Manson-Coffin equation,LV model,and FS model are compared with the experimental results.The comparison results show that the prediction accuracy of the proposed model is better than the other three models.
万方数据
维普
