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).