How to give damage criteria?
Vivekananda Halda
James M. Kennedy
Dear Vivek,
See if these are of some interest:
*MAT_ADD_GENERALIZED_DAMAGE
This option provides a way of including generalized (tensor type) damage and failure in standard LS-DYNA material models. The basic idea is to apply a general damage model (e.g. GISSMO) using several history variables as damage driving quantities at the same time. With that feature it may be possible to obtain e.g. anisotropic damage behavior or separate stress degradation for volumetric and deviatoric deformations. A maximum of three simultaneous damage evolutions (i.e. definition of 3 history variables) is possible. A detailed description of this model can be found in Erhart et al. [2017]. This option currently applies to shell element types 1, 2, 3, 4, 16, and 17 and solid element types -2, -1, 1, 2, 3, 4, 10, 13, 15, 16, and 17.
*MAT_ADD_GENERALIZED_DAMAGE is a highly flexible damage/failure model that can consider orthotropic damage but also damage due to different contributions (e.g., deviatoric and volumetric). In case of orthotropic damage, special components of the plastic strain tensor are evaluated. These are the drivers for the damage accumulation in three material directions. A reasonable description of orthotropic plasticity is crucial for accurate plastic strains and, therefore, for an accurate failure prediction:
Andrade, F., Erhart, T., and Haufe, A. "Modeling of Anisotropic Damage with *MAT_ADD_GENERALIZED_DAMAGE", 2016 Nordic LS-DYNA Users Forum, Gothenburg, Sweden, October, 2016.
An introduction of a new generalized damage model (*MAT_ADD_GENERALIZED_ DAMAGE/*MAT_AGD) was given which can be added to many existing models in a modular fashion. It was shown that it serves as a very flexible tool to describe multi-parameter anisotropic damage and failure. In this paper, a first introduction into the topic was given, explained input parameters and various options of the new keyword and, finally, used different numerical examples to shed some light on its usage. The focus was not on specific material types, but rather on the demonstration of fundamental features:
Erhart, T., Du Bois, P., and Andrade, F., "Short Introduction of a New Generalized Damage Model", 11th European LS-DYNA Users Conference, Salzburg, Austria, May, 2017.
Due to pronounced anisotropic flow the prediction of failure in aluminum extrusions has been an elusive goal. Progress has been made due to extensive code development in both plasticity (*MAT_036E) and anisotropic failure (*MAT_ADD_GENERLIZED_ DAMAGE/*MAT_AGD). The orthotropic failure model in *MAT_AGD is believed to be the only failure model that allows for directional dependency of the failure strain upon the state of stress:
Du Bois, P., "Anisotropic Plasticity, Anisotropic Failure and Their Application to the Simulation of Aluminum Extrusions under Crash Loads", Oasys LS-DYNA UK Users Meeting, Solihull, United Kingdom, January, 2016.
http://www.oasys-software.com/dyna/en/events/users_jan-16/Papers/PDB_keynote-arup-release.pdf
Due to pronounced anisotropic flow the prediction of failure in aluminum extrusions has been an elusive goal. Progress has been made due to extensive code development in both plasticity (*MAT_036E) and anisotropic failure (*MAT_ADD_GENERLIZED_ DAMAGE/*MAT_AGD). The orthotropic failure model in *MAT_AGD is believed to be the only failure model that allows for directional dependency of the failure strain upon the state of stress:
Du Bois, P., Erhart, T., Andrade, F., Haufe, A. Neukamm, F., Feucht, M., and Irslinger, J., "A New Versatile Tool for Simulation of Failure in LS-DYNA and the Application to Aluminum Extrusions", 14th German LS-DYNA Forum, Bamberg, Germany, October, 2016.
Quasi-static tensile tests, dynamic tensile tests and three point bending tests were performed to determine the strain rate behavior of the material. For the first step the coupon testes were simulated with von Mises plasticity (*MAT_024). In a next step the plastic Poisson’s ratio was taken into account by using SAMP-1 material model (*MAT_187) in order to model and consider the increasing volumetric strain with increasing tensile load. Finally fracture modeling with increasing volumetric straining with the eGISSMO model (*MAT_ADD_GENERALIZED_DAMAGE) was shown:
Helbig, M., and Haufe, A., "Testing and Modelling of Rubber-Toughened Polymers with LS-DYNA", 15th German LS-DYNA Forum, Bamberg, Germany, October, 2018.
A reasonable description of orthotropic plasticity is crucial for accurate plastic strains and, therefore for an accurate failure prediction. In the case of orthotropic damage, special components of the plastic strain tensor are needed. There are the drivers for the damage accumulation in three material directions. *MAGD (eGISSMO) is a highly flexible damage/failure model that can consider orthotropic damage, among other things (e.g., deviatoric and volumetric splitting):
Koch, D., Andrade, F., Du Bois, P., Feucht, M., and Haufe, A., "On the Development of the New Generalized Orthotropic Damage and Fracture Model eGISSMO", 15th German LS-DYNA Forum, Bamberg, Germany, October, 2018.
In order to simulate the pull-out forces of a screw, the finite element method was employed, simulation models from three different material models selected from the Finite Element Analysis (FEA) software LS-DYNA. The first material model considered Mat_143, a wood material model based on the Hashin failure criterion and used to develop simulation model 1. The second material considered, *MAT_122 3D, based on Hill’s plasticity theory, was used with *MAT_ADD_GENERLIZED_ DAMAGE to allow for incremental damage accumulation and failure. This was simulation model 2. The third one, Mat_221 which represents an orthotropic material with simplified damage, was used to develop simulation model 3
Phiri, T., and Bjorkman, N., “Simulating Pull-Out Fracture in Particleboard”, Master’s Thesis, Department of Mechanical Engineering, Linkoping University, Linkoping, Sweden, Spring, 2019.
http://liu.diva-portal.org/smash/get/diva2:1413908/FULLTEXT01.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
April 3, 2022
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