  The accurate and efficient modeling of granular flows and their interactions
with external bodies is an open research problem. Continuum methods can be used
to capture complexities neglected by terramechanics models without the
computational expense of discrete element methods. Constitutive models and
numerical solvers are the two primary aspects of the continuum methods. The
viscoplastic size-dependent non-local granular fluidity (NGF) constitutive
model has successfully provided a quantitative description of experimental
flows in many different configurations in literature. This research develops a
numerical approach, within a hyperelasticity framework, for implementing the
dynamical form of NGF in three-dimensional material point method (3D MPM, an
appropriate numerical solver for granular flow modeling). This approach is
thermodynamically consistent to conserve energy, and the dynamical form
includes the nonlocal effect of flow cessation. Excavation data, both
quantitative measurements and qualitative visualization, are collected
experimentally via our robotic equipment to evaluate the model with respect to
the flow geometry as well as interaction forces. The results are further
compared with the results from a recent modified plastic Drucker-Prager
constitutive model, and in other configurations including wheel-soil
interactions, a gravity-driven silo, and Taylor-Couette flow.
