An analysis of failure in shear versus tension.

The micromechanics of ductile failure is revisited using the voided cell model. Emphasis is laid on comparing shearing stress states with axisymmetric states. The unit cell is subjected to proportional loading and fully periodic boundary conditions. The progression of elastic unloading in the unit cell is analyzed, leading to a definition of unhomogeneous yielding. Overall strain localization is determined by evaluating "on the fly" the tangent operator using a perturbation method. The connection between unhomogeneous yielding and strain localization is thus thoroughly investigated. Other potentially critical strain measures are introduced and their relevance to failure by void coalescence or strain localization is discussed. The effects of initial porosity and strain hardening in modulating the relative ductility under tension versus shear are further examined. • Voided unit cell calculations are carried out under fully periodic boundary conditions. • Unhomogeneous yielding is defined based on the percolation of elastically unloaded domains. • Strain localization is analyzed using a perturbation method. • In all cases, strain localization is found to occur after the onset of unhomogeneous yielding. • The common trend that axisymmetric stress states are "more ductile" than shearing states is found to break down. [ABSTRACT FROM AUTHOR]