Plasticity Drucker - Prager Model

The yield criterion can be defined as:

where α and κ are material constants which are assumed unchanged during the analysis, σm is the mean stress and σ(bar) is the effective stress.

α and κ are functions of two material parameters φ and c obtained from experiments, where φ is the angle of internal friction and c is the material cohesion strength.

The Drucker-Prager model can be used to simulate the behavior of granular soil materials such as sand and gravel. In using this material model, the following considerations should be noted:
  • Strains are assumed to be small.
  • Problems with large displacements can be handled provided that the small strains assumption is still valid.
  • The use of the NR (Newton-Raphson) iterative method is recommended.
  • Material parameters φ and c must be bounded in the following ranges:
    • 0 <= φ <= 90 (in degrees)
    • c >= 0 (in force/unit area)
  • For most soil mechanics problems, gravitational acceleration can have significant effect, therefore gravitational acceleration should be defined through the Gravity PropertyManager.
The required inputs include the following:
  • Elastic modulus and Poisson's ratio
  • Material cohesion strength
  • Friction angle

The Drucker-Prager model can be used with the solid elements (draft and high quality mesh).