Using the algorithm above, the uniaxial compression test shows a strain softening behavior. Strain softening (Fig. 8 left) is associated with shear localization that leads to faulting (Fig. 8 top and bottom right). Under plane-strain conditions, with simple neck geometries and zero/low friction...
(Wt,αt) represents the parameters already estimated in the previous iteration while (Wt+1,αt+1) is updated via a standard gradient descent algorithm from (Wt,αt). For the first iteration (t = 0), we use nominal initial parameters,W0andα0. ...