A rate-dependent model for sand to predict constitutive response and instability onset

A constitutive model has been proposed for predicting rate-dependent stress-strain response of sand and further implemented in finite element code to explore the influence of strain rate on the localization behavior of sand. The proposed model simulates various constitutive features of sand subjected to higher strain rates, e.g., enhanced shear strength, early peak followed by a softening response, reduced compression for loose sand, etc., which have been reported in the literature. Numerical simulations predict a delayed onset of strain localization and increase in the band angle with increasing strain rate. Strains are noticed to localize in the hardening regime for loose sand, whereas for denser state localization emerges in the post-peak regime.