Figure 6.

The engineering stress–strain responses for specimen 1 calculated at different biaxiality ratios. The critical points for the onset of "pattern transformation III" (PT III) or PT II are marked by dark-red or red circles on these curves. Pattern transformation III was only observed for specimen 1 with an oblique lattice of voids under biaxial compression. The solid lines and the dotted lines stand for the engineering stress ${\Sigma }_x$ in the direction of x and ${\Sigma }_y$ in the direction of y, respectively.