Fatigue crack growth studies under mixed-mode loading

In this study, the growth behavior of fatigue cracks in AISI-304 stainless steel samples under mixed-mode (mode-I and mode-II) loading conditions was studied by utilizing Compact Tension Shear Specimen (CTS) geometry. The results indicate that, at low load mixities, both the strain energy density criterion and the maximum stress criterion estimate similar crack growth directions; however, at high load mixities, the maximum stress criterion provides a closer estimation what is observed in experiments. Mixed-mode loading has a pronounced effect on the growth rate of cracks, and on the growth behavior after the over loads at identical applied load levels. Crack closure concepts seem to be inadequate to fully describe the observed fatigue crack growth behaviour under mixed-mode loading.