Influence of non-local strain regularization on the evolution of shear bands

The numerical analysis of strain softening problems by means of the conventional finite element method is well known to suffer from severe mesh dependency, and various approaches have been proposed to overcome this deficiency. Among these, the non-local approach has received increasing attention over the last two decades due to its relatively simple implementation and mechanically plausible assumptions. In this study the consequences of different assumptions for the non-local strain regularization are investigated with regard to the evolution of shear bands. A partially non-local approach has been implemented into a multilaminate constitutive model. The constitutive model employs a Hvorslev surface to describe peak shear strength and dilatancy in the heavily overconsolidated range. It is shown that the numerical shear band in biaxial test simulations rotates in softening and settles at ~45° if softening is allowed to spread to stress points outside the initial shear band. This contradicts experimental
findings, which show much steeper and virtually constant shear bands. Limiting strain regularization to stress points at or close to failure provides significantly better match with the experimental data