Eric B. Herbold

A continuum model for concrete informed by mesoscale studies

The paper describes a novel computational approach to refine continuum models for penetration calculations which involves two stages. At the first stage, a trial continuum model is used to model penetration into a concrete target. Model parameters are chosen to match experimental data on penetration depth. Deformation histories are recorded at few locations in the target around the penetrator. In the second stage, these histories are applied to the boundaries of a representative volume comparable to the element size in large scale penetration simulation. Discrete-continuum approach is used to model the deformation and failure of the material within the representative volume. The same deformation histories are applied to a single element which uses the model to be improved. Continuum model may include multiple parameters or functions which cannot be easily found using experimental data. We propose using mesoscale response to constrain such parameters and functions. Such tuning of the continuum model using typical deformation histories experienced by the target material during the penetration allows us to minimize the parameter space and build better models for penetration problems which are based on physics of penetration rather than intuition and ad hoc assumptions.

Characterization of the crystal structure, kinematics, stresses and rotations in angular granular quartz during compaction

Three-dimensional X-ray diffraction and X-ray computed tomography are used to study the grain-scale response of angular granular materials to understand grain kinematics, stresses and rotations during compaction and to compare the responses of angular grains with those of spherical grains.