The response of concrete and mortar under high-strain-rate impact loading a
re analyzed using fully dynamic finite element simulations. The analyses co
ncern the load-carrying capacity, energy absorbency and the effect of the m
icrostructure. The simulations focus on the plate impact configuration used
in the experimental part of this research, allowing for direct comparison
of model predictions with experimental measurements. A micromechanical mode
l is formulated and used, accounting for the two-phase composite microstruc
ture of concrete. Arbitrary microstructural phase morphologies of actual co
ncrete used in impact experiments are digitized and explicitly considered i
n the numerical models. The behavior of the two constituent phases in the c
oncrete are characterized by an extended Drucker-Prager model that accounts
for pressure-dependence, rate-sensitivity, and strain hardening/softening.
Model parameters are determined by independent impact experiments on morta
r and through a parametric study in which the prediction of numerical simul
ations is matched with measurements from experiments on concrete and mortar
. Calculations show that significant inelastic deformations occur in the mo
rtar matrix under the impact conditions analyzed and relatively smaller ine
lastic strains are seen in the aggregates. The influence of aggregate volum
e fraction on the dynamic load-carrying capacity of concrete is explored. T
he strength increases with aggregate volume fraction and an enhancement of
approximately 30% over that of mortar is found for an aggregate volume frac
tion of 42%. Numerical simulations also show increasing energy absorbency w
ith increasing aggregate volume fraction and provide a time-resolved charac
terization for the history of work dissipation as the deformation progresse
s. (C) 2001 Elsevier Science Ltd. All rights reserved.