Nonlocal modeling of softening in hypoplasticity: Fid-Bau Portal

Nonlocal modeling of softening in hypoplasticity

Maier, Th.

AbstractThe present paper deals with a nonlocal hypoplastic model for granular materials like e.g. sands. The nonlocal formulation is based on a scalar variable which is a certain weighted average of the local variable taken from all material points under consideration. An internal length scale enters the constitutive equation as an additional material parameter of the Gaussian weighting function. A relation between the internal length scale and the mean grain diameter is derived for dense sands from numerical calculations and experimental results of biaxial tests. The proposed nonlocal theory preserves well-posedness of the governing equations in the post-localization regime and prevents pathological mesh sensitivity of the numerical results e.g. in biaxial tests and the strip foundation problem. The ability of the presented model to describe the behaviour of granular materials is demonstrated by comparisons of the results of numerical calculations and laboratory tests.