Multisurface plasticity for 2D models

Implementation of a robust multisurface return-mapping algorithm in Abaqus, dedicated for 2D models. Those files are based on the original work by Sebastian Pech and Markus Lukacevic. The present version contains modifications made by Jan Pełczyński from Warsaw University of Technology. The original work is published at https://gitlab.imws.tuwien.ac.at/e202-02/multisurface-plasticity/ Modifications - The algorithm was limited to one Tsai-Wu plasticity surface. - The number of <i>Mechanical Constants</i> entered in the <i>User Material</i> module was changed. The nine elasticity tensor parameters were replaced by four. Six Tsai-Wu yield surface parameters were added for easier communication with the Fortran subroutine. - The dimensions of the arrays received from Abaqus and sent back have been changed so that the passed parameters correspond to a plane stress state. - The dimensions of all vectors and matrices have been reduced and some formulas have been changed to correspond to a plane stress state. Publication This project is licensed under the GNU General Public License v3.0.If you find the subroutines useful in your work (research only), please cite all publications connected to the dataset in the repository and papers of the original authors: 1. Pech S, Lukacevic M, Füssl J. A robust multisurface return-mapping algorithm and its implementation in Abaqus. Finite. Elem. Anal. Des., 2021, 190, 103531, doi: [10.1016/j.finel.2021.103531](https://doi.org/10.1016/j.finel.2021.103531)2. Lukacevic M, Lederer W, Füssl J. A microstructure-based multisurface failure criterion for the description of brittle and ductile failure mechanisms of clear-wood.Eng. Fract. Mech., 2017, 176, 83-99, doi: [10.1016/j.engfracmech.2017.02.020](https://doi.org/10.1016/j.engfracmech.2017.02.020)3. Lukacevic, M, Füssl, J, Lampert R. Failure mechanisms of clear wood identified at wood cell level by an approach based on the extended finite element method.Eng. Fract. Mech., 2015, 144, 158-175, doi: [10.1016/j.engfracmech.2015.06.066](https://doi.org/10.1016/j.engfracmech.2015.06.066) Authors Jan Pełczyński ([e-mail]), Warsaw University of Technology, Faculty of Civil Engineering, Al. Armii Ludowej 16, 00-637 Warsaw. Running the calculation and input file configuration Described in the Readme file.