blockresearchgroup / compas_cra

Coupled Rigid-Block Analysis: Stability-Aware Design of Complex Discrete-Element Assemblies

COMPAS CRA

Coupled Rigid-Block Analysis (CRA) implementation using COMPAS framework.

developed with ♥ by Gene Ting-Chun Kao

To find out more about CRA, please refer to our paper in the CAD Computer-Aided Design journal: https://doi.org/10.1016/j.cad.2022.103216

Coupled Rigid-Block Analysis: Stability-Aware Design of Complex Discrete-Element Assemblies

Abstract

The rigid-block equilibrium (RBE) method uses a penalty formulation to measure structural infeasibility or to guide the design of stable discrete-element assemblies from unstable geometry. However, RBE is a purely force-based formulation, and it incorrectly describes stability when complex interface geometries are involved. To overcome this issue, this paper introduces the coupled rigid-block analysis (CRA) method, a more robust approach building upon RBE’s strengths. The CRA method combines equilibrium and kinematics in a penalty formulation in a nonlinear programming problem. An extensive benchmark campaign is used to show how CRA enables accurate modelling of complex three-dimensional discrete-element assemblies formed by rigid blocks. In addition, an interactive stability-aware design process to guide user design towards structurally-sound assemblies is proposed. Finally, the potential of our method for real-world problems are demonstrated by designing complex and scaffolding-free physical models.

Please cite our work if you use CRA in your research

Paper

@article{kao2022coupled,
    title     = {Coupled Rigid-Block Analysis: Stability-Aware Design of Complex Discrete-Element Assemblies},
    author    = {Kao, Gene Ting-Chun and Iannuzzo, Antonino and Thomaszewski, Bernhard and Coros, Stelian and Van Mele, Tom and Block, Philippe},
    journal   = {Computer-Aided Design},
    volume    = {146},
    pages     = {103216},
    year      = {2022},
    publisher = {Elsevier},
    doi       = {10.1016/j.cad.2022.103216},
    url       = {https://doi.org/10.1016/j.cad.2022.103216}
}

Software implementation

@misc{compas-cra,
    title  = {{COMPAS CRA}: Coupled Rigid-Block Analysis ({CRA}) for the {COMPAS} framework},
    author = {Kao, Gene Ting-Chun},
    note   = {https://github.com/BlockResearchGroup/compas\_cra},
    year   = {2020-2022},
    doi    = {10.5281/zenodo.7043135},
    url    = {https://doi.org/10.5281/zenodo.7043135},
}

Read the docs

https://blockresearchgroup.github.io/compas_cra

Examples to reproduce our paper results

See examples in docs or try them in docs/examples.

compas_cra's Issues

new pyomo does not work with the package

Describe the bug

Some namespaces have been renamed apparently in the new pyomo and so the package does not work with the new version of pyomo (6.5). I need to every back to an older version equal to the one used at the time of development but I don't know what version that is. While you are working on an update, could you please kindly mention the version of pyomo or export your conda environment as a yml file to help avoid similar issues?
To Reproduce

Steps to reproduce the behavior:

I am running your code in a Jupyter Notebook.
Try running this with a new pyomo (6.5):

from compas_cra.equilibrium import cra_solve
cra_solve(assembly, verbose=True, timer=True)

see error:
AttributeError: module 'pyomo.environ' has no attribute 'ConcreteModel'

Rhino export

Hi,

I'm trying to export a simple two block model out of Rhino. For exporting the geometry, I stick to the tutorial provided on the documentation site. When continuing in VS Code, I still continue as shown in the tutorial, as you can see below. When I try to solve the assembly using cra_solve, the following error occured: "IndexError: index(71) out of range".
Does someone know why I run into this error? Below you can find my VS Code and attached there are .txt files (.json not supported to upload) of the two blocks (test10 in pretty and test11 in normal).

Thanks in advance and best,
Dario

import os
import compas
import compas_cra

from compas_cra.datastructures import CRA_Assembly
from compas_cra.algorithms import assembly_interfaces_numpy
from compas_cra.equilibrium import cra_solve
from compas_cra.viewers import cra_view

FILE_I = os.path.join(compas_cra.DATA, "test11.json")
assembly = compas.json_load(FILE_I)
assembly = assembly.copy(cls=CRA_Assembly)

assembly.set_boundary_conditions([0])

assembly_interfaces_numpy(assembly)

cra_solve(assembly, verbose=True, timer=True)

cra_view(assembly, resultant=False, nodal=True, grid=True)

test10.txt
test11.txt

maxIterations

Hi everyone

While using the cra_solve function, I'm often running into the following error:
" ValueError: maxIterations"

Is there a way of bypassing this error (allow more Iterations or change some other parameters as d_bnd or eps)?