Scatter in the fatigue characteristics of steels and its analysis with allowance for cyclic inelastic strains

The regularities of the scatter in the characteristics of fatigue and inelasticity of steels 45 and 1Kh13 have been studied under steady-state, step, and block loading. It is shown that the use of the inelastic strain per cycle as a measure of the fatigue damage accumulation rate makes it possible to take into account the scatter in the number of cycles to fracture and in the fatigue limits and to substantiate the cumulative fatigue damage rule. __________ Translated from Problemy Prochnosti, No. 3, pp. 5–22, May–June, 2007.     

On combination of the equivalent material concept and J‐integral criterion for ductile failure prediction of U‐notches subjected to tension

The aim of the present research is to check the capability of the equivalent material concept (EMC) combined with the J‐integral failure criterion, called EMC‐J criterion, in predicting the load‐carrying capacity (LCC) of U‐notched ductile aluminium plates subjected to tension by considering the 2 moderate and large‐scale yielding regimes. For this purpose, first, a set of experimental results on LCC of 2 groups of thin U‐notched rectangular plates made of Al 7075‐T6 and Al 6061‐T6 are gathered from the recent literature. Then, because the Al 7075‐T6 and Al 6061‐T6 plates have ductile behaviour, EMC is employed to avoid performing elastic‐plastic failure analysis for LCC predictions. Up to now, different failure models in the context of the linear‐elastic notch fracture mechanics have been successfully utilized in combination with EMC for ductile failure prediction of notched members. However, this is the first time in this research that J‐integral, as a well‐known brittle failure criterion, is linked to EMC for predicting LCC of the U‐notched rectangular aluminium plates. Finally, it is shown that EMC‐J criterion can predict well the experimental results of tensile LCC.     

Analysis of the influence of the level of residual stresses on the ultimate stresses in a cycle for welded structures according to the results of testing of small-size specimens

We propose a procedure for the determination of the diagrams of ultimate stresses in a cycle for welded joints with preliminarily induced steady-state residual stresses according to the results of testing of small-size specimens without residual stresses. Translated from Problemy Prochnosti, No. 3, pp. 107–115, May–June, 2009.