r7.01.22 Law of viscoplastic behavior VISC_DRUC_PRAG

Summary:

This document describes the law of viscoplastic behavior VISC_DRUC_PRAG based on the elastoplastic Drucker-Prager model and taking into account viscosity according to a Perzyna power law. Its field of application is argillite, which is the host rock for the storage concept.

The proposed model includes a single viscoplastic mechanism. The criterion collapses with the cumulative viscoplastic deformation by passing through three thresholds: elastic, peak and ultimate. The flow is not associated, the flow potential being a Drucker-Prager potential falling at three levels: elastic, peak and ultimate. Between the thresholds, the workings are linear.

This law can be used in pure mechanical modeling as it can be used in a THM modeling. It is available in 3D, plane and axisymmetric deformations. It is integrated by solving a single non-linear scalar equation.

Table of Contents

• 1. Notations
• 2. Introduction
• 3. Formulation of the viscoplastic model VISC_DRUC_PRAG
  • 3.1. Model equations
• 4. Code_Aster integration
  • 4.1. Deformation tensor decomposition
  • 4.2. Update constraints
  • 4.3. Coherent tangent operator
  • 4.4. Material data
  • 4.5. The internal variables
  • 4.6. Summary of the resolution algorithm
• 5. Results of a triaxial test
• 6. Features and verification
• 7. References
• 8. Description of the versions of the document