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MAT_CDPM (MAT_273) in LS-DYNA

This page provides information for MAT_CDPM (MAT_273) in LS-DYNA. This information is provided as is, and no guarantee is given that it will help the code to preform in the desired way. Do you have any useful information about this material model and are willing to share it with others? Please get in touch with Peter Grassl so that we can add it to this page. Most of the examples provided here were performed with the double precision version of Release 9.1. It is strongly recommended to use this release (or higher) together with MAT_273.

Outline

Background

On this page information about the concrete damage plasticity constitutive model MAT_CDPM (MAT_273) in LS-DYNA is provided. This model is based on work published in Grassl and Jirásek (2006) (DOI), Grassl et al. (2011) (Preprint) and Grassl et al. (2013) (DOI, Preprint).

In Grassl and Jirásek (2006), the main framework of the present damage plasticity model was developed, which was called CDPM. In this work an effective stress based plasticity model was combined with a scalar damage approach with one damage variable for both tension and compression. The effective plasticity part was designed to describe the pressure sensitive hardening response. For the post-peak regime a perfect plastic response was chosen and softening was described by the damage part.

Peter Grassl from the University of Glasgow proposed in collaboration with Kent Gylltoft, Rasmus Rempling and Ulrika Nyström from Chalmers University in Sweden, an extension of the CDPM, which was called CDPM2. A short description of the new model was published first in a conference paper in Grassl et al. (2011). Three main changes in CDPM2 (compared to CDPM) were introduced:

Subsequently, the first two modifications of CDPM2 described in the conference paper (hardening in the post-peak regime and introduction of two damage variables) were refined and described in more detail in the journal article Grassl et al. (2013) together with Dimitrios Xenos. The approach to model strain rate dependence was not changed and was not included again in Grassl et al. (2013). For obtaining a detailed description of CDPM2, it is recommended to study Grassl et al. (2013). For the way how strain rate dependence is considered, it is referred to Grassl et al. (2011).

CDPM2 was implemented in LS-DYNA for the first time around 2013/14. In LS-DYNA it is called simply MAT_CDPM (or MAT_273). In 2015, Dimitrios Xenos and Peter Grassl reimplemented it to increase its robustness. This improved version is available in Release 9.1 onwards.

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Input for MAT_CDPM

Our version of the description of the input parameters for MAT_CDPM (MAT_273) for Release 9.1 onwards is available below with additional explanation:

User manual for MAT_CDPM (MAT_273) in LS-DYNA (Last updated: 11 November 2016)

It is strongly recommended to use MAT_CDPM in at least Release 9.1, since this release includes the new implementation with improved robustness (see the background section). Tetrahedral elements together with MAT_CDPM are only available in this later version.
If you have any comments/questions concerning this user manual for MAT_CDPM, please feel free to contact Peter Grassl so that it can be improved.

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User material subroutine

Fortran file for user material version of MAT_CDPM for UMAT50V and UTAN50V (only elastic stiffness for now):

cdpm2umat.f (Last update 21 April 2016)

Example material card for the user material:

materialUser.k (Last update 21 April 2016)

For including this model into LS-DYNA, you need to comment out the subroutines for UMAT50V and UTAN50V in "dyn21.f" and include "cdpm2umat.f". If you find any bugs in this user material version of MAT_CDPM or are able to provide improvements, please let us know by contacting Peter Grassl so that we can fix it and update it on this page.

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Key references for the theory of MAT_CDPM (MAT_273) in LS-DYNA

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References using MAT_CDPM (MAT_273) in LS-DYNA

Note: If you have publications (theses, conference papers, technical reports, journal articles) in which you have used MAT_CDPM (MAT_273) in LS-DYNA and which you would like to share with others, please send them toPeter Grassl. We will post them here, so that others can make use of your experience with MAT_CDPM in LS-DYNA. Even if it is only a small section on MAT_CDPM (MAT_273), it still might be of use for other researchers.

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Example input files

Note: If you have example input files that you would like to share, please send them to Peter Grassl together with a short description. I will post them then here.

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Frequently Asked Questions

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Useful links

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Last updated by Peter Grassl