Plasticity in OOF

Summary

We discuss recent advances in the Object Oriented Finite-Element project at NIST, a Python and C++ tool designed to bring sophisticated numerical modeling capabilities to users in the field of Materials Science.

Description

We discuss recent advances in the Object Oriented Finite-Element project at NIST (also called OOF), a Python and C++ tool designed to bring sophisticated numerical modeling capabilities to users in the field of Materials Science.

As part of the effort to expand the solid-mechanics capabilities of the code, the solver has been extended to include the ability to handle history-dependent properties, such as occur in viscoplastic systems, and inequality constraints, which are present in conventional isotropic plasticity, as well as surface interactions.

This software provides numerous tools for constructing finite-element meshes from microstructural images, and for implementing material properties from a very broad class which includes elasticity, chemical and thermal diffusion, and electrostatics.

The code is a hybrid of Python and C++ code, with the high level user interface and control code in Python, and the heavy numeric work being done in C++. Numerous tools are provided for constructing finite-element meshes from microstructural images, and for implementing material properties from a very broad class which includes elasticity, chemical and thermal diffusion, and electrostatics. The software can be operated either as an interactive, GUI-driven application, as a scripted command-line tool, or as a supporting library, providing useful access to users of varying levels of expertise. At every level, the user-interface objects are intended to be familiar to the materials-science user.

The modular object-oriented design of the code, and the strategy of separating the finite-element infrastructure from the material constitutive rules proved itself in implementing the new solid-mechanics capabilities.

Development on a fully-3D version of the code has also made significant progress, overcoming several challenges associated with user-interface issues. A nontrivial, solved 3D problem will be presented.