TARDIGRADE-EXAMPLES

Tardigrade-examples (LANL code O4735) is a repository of computational workflows that exercise the Tardigrade software package.

The Tardigrade software package is an implementation of Eringen’s micromorphic continuum theory with capabilities to support multiscale material modeling workflows. These capabailities include homogenization through the Micromorphic Filter, calibration of micromorphic materials models, and macroscale simulation in Tardigrade-MOOSE.

This repository investigates continuum upscaling of various direct numerical simulations (DNS) conducted in Abaqus finite element (FE), Ratel FE, and GEOS material point method (MPM) software. Verfication of the upscaling workflow is first investigated by considering DNS of trivial stress states for homogeneous materials, results of which indicate that classical continuum behavior is recovered as expected. DNS of heterogeneous materials are then considered.

Description

Tardigrade-examples includes upscaling analyses of a variety of DNS. The WAVES computational workflow tool is used to automate these studies in a reproducible manner primarily through a collection of Python scripts.

A full upscaling study considers four main analysis stages:

  1. DNS

  2. Filter

  3. Calibrate

  4. Tardigrade-MOOSE

The included DNS investigate simple compression of a homogenoeous cylinder. Alternatively, externally performed DNS results may be upscaled that consider more interesting materials and stress states. DNS results are post-processed into the XDMF file format required by the Micromorphic Filter. This repository currently includes Python scripts for XDMF conversion of the Abaqus output database (ODB) and Ratel visualization toolkit (VTK) formats, with GEOS MPM VTK coming soon.

The Micromorphic Filter homogenizes DNS results onto a macroscale mesh where each element is considered a “filtering domain.” Meshes are generated using Cubit. For users without access to Cubit, a collection of example meshes are included, but functionality is limited. Upscaling workflows consider macroscale meshes of varying element size using WAVES parametric study tools to analyze how homogenization changes as the number of filtering domains increase.

The homogenized, micromorphic stress and deformation measures output by the Micromorphic Filter are used to calibrate various material models. A unique calibration for each filtering domain (macroscale element) is produced. For verification studies of simple DNS, classical inear elasticity is calibrated, while several forms of micromorphic linear elasticity are calibrated for heterogeneous DNS. Calibration of elasto-plasticity will be included in a future release of this repository.

Finally, material calibration results are applied to macroscale simulations in Tardigrade-MOOSE with similar boundary and loading conditions as the original DNS. Python scripts are included that collect and summarize results across parametric studies for different analysis stages.

Documentation is included which details the upscaling methodology, steps for building and connecting required software, relevant micromorphic theory, how the Micromorphic Filter works, constitutive theories, and results of several upscaling studies.

Micromorphic Upscaling Workflow

Software Requirements

Quasi-static Verification

Dynamic Verification

Heterogeneous Upscaling

Model Repository

Help & Reference

Appendix - Detailed Theory

Indices and tables