On the study of the effect of Luders plateau on fracture response with cohesive zone model

Abstract

For materials presenting Lüders plateau, low temperatures in the Arctic region will prolong the plateau length. In this study, the effect of Lüders plateau on crack growth resistance has been investigated with cohesive zone model, bilinear traction-separation and the single edge notched tensile (SENT) specimens. The Lüders plateau is simplified by keeping the plateau stress constant and equaling to the yield stress. A family of Lüders plateau ranging from 0 to 0.1 are analyzed. Constraint analysis with the modified boundary layer (MBL) model shows that the introduction of the Lüders plateau reduces crack tip constraint. Longer Lüders plateau corresponds to larger reduction. Numerical results show that the effect of Lüders plateau on crack growth resistance is insignificant when the cohesive energy is very small. With the increase of the cohesive energy, the effect of the Lüders plateau on crack growth resistance are observed and material with longer Lüders plateau yields higher resistance curve. In addition, effects of the crack depth and the maximum traction stress on the resistance curves are also briefly discussed.