Mesh dependency and regularization methods in FE-calculations within hypoplasticity

Failure of granular materials is commonly associated with localization of deformation in zones of intense shearing like shear bands. The realistic modelling of shear bands is of essential importance in numerical calculations within the FE-method. Classical, i.e. local continuum theories are inappropriate for modelling materials with strong strain softening due to a missing characteristic length scale. Therefore, numerical computations based on classical continuum theories result in a serve mesh dependence. Here, three regularization methods within the framework of hypo-plasticity are introduced. The determination of the characteristic length scale is given and their computational robustness in terms of mesh in-sensitivity demonstrated. Further, the three methods are compared by calculating laboratory tests and the strip foundation problem.