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title Two-scale notch
permalink tutorials-two-scale-notch.html
keywords Macro-micro, Micro Manager, CalculiX, FANS, FE-FFT
summary We solve a two-scale notch problem with a micro-structure based material. One macro simulation is coupled to several micro simulations using the Micro Manager.

{% note %} Get the case files of this tutorial. Read how in the tutorials introduction. {% endnote %}

Setup

This tutorial solves a linear elastic static problem on a 3D notch geometry which has an underlying micro-structure. The notch is fixed at one end and has a force boundary condition at the other end.

Von Mises stress on macro scale

The micro-structure is a 3D sphere enclosed in a unit square box.

Micro structure

The micro-structure needs to be evaluated to obtain the stresses and the material stiffness matrix, both necessary for solving the problem on the macro scale. This leads to a two-scale problem with one macro-scale simulation and several micro-scale simulations.

At each Gauss point of the macro domain there exists a micro simulation. The macro problem is one participant, which is coupled to many micro simulations. Each micro simulation is not an individual coupling participant, instead we use the Micro Manager, which controls all the micro simulations and is itself a coupling participant.

Configuration

preCICE configuration (image generated using the precice-config-visualizer):

preCICE configuration visualization

Available solvers and dependencies

  • The macro notch problem is solved using CalculiX, so it required the CalculiX adapter.
  • The micro problem is solved using FANS. FANS needs to be compiled in a Python-wrapped library form, check the documentation on how to do this.
  • The Micro Manager controls all micro-simulations and facilitates coupling via preCICE. Use the develop branch of the Micro Manager.

Running the simulation

You can find the corresponding run.sh script for running the case in the folders corresponding to the solvers you want to use.

Run the macro problem:

cd macro-calculix
./run.sh

Check the Micro Manager configuration and running documentation to understand how to set it up and launch it. The Micro Manager can be run via this script in serial or parallel. Run it in serial:

cd micro-fans
./run.sh -s

Running the simulation in parallel

cd micro-fans
./run.sh -p <num_procs>

The num_procs needs to fit the decomposition specified in the micro-manager-config.json (default is serial). See the documentation on how to set domain decomposition in the Micro Manager configuration.

NOTE: When running micro-fans, even though the case setup and involved physics is simple, each micro simulation is a FANS simulation with a mesh of 32x32x32 nodes, which usually has a moderately high computation time. If the Micro Manager is run in serial, the total runtime is approximately 30 minutes.

Post-processing

The final von Mises stress on the macro scale look like

Von Mises stress on macro scale

The result is generated by converting the CalculiX .frd output file to a VTU or VTK file using ccx2paraview, and visualizing it in ParaView.