r3.06.09 Mechanical joint finite elements and hydromechanically coupled joint finite elements

Summary:

This documentation relates to the description of the finite elements of linear and quadratic mechanical joints. Pure mechanical models (xxx_ JOINT) support both types of meshes, while coupled hydromechanical models (xxx_ JOINT_HYME) are only implemented for quadratic meshes. Fictional pressure degrees of freedom are eliminated for quadratic models in pure mechanics. These models make it possible to simulate the evolution of a crack along a predetermined path. The second type of element also takes into account the interaction of mechanics with a flow of fluid inside the crack.

The following points are presented in succession:

1. geometry of the elements

2. local coordinate system at the joint and matrix for the transition from the global coordinate system to the local coordinate system

3. displacement jump in the joint

4. fluid pressure gradient

5. nodal vector of internal forces as well as the elementary tangent matrix

• 1. Geometry of elements
  • 1.1. 2D linear joint geometry
  • 1.2. 2D quadratic joint geometry
  • 1.3. 3D linear joint geometry
  • 1.4. 3D quadratic joint geometry
  • 1.5. Automatic joint mesh construction
• 2. Local coordinate system and transition matrix
  • 2.1. 2D case
  • 2.2. 3D case
• 3. Move jump
• 4. Fluid pressure gradient
• 5. Inner forces and tangent matrix
  • 5.1. Pure mechanical case
  • 5.2. Hydromechanical coupled case
• 6. Features and validation
• 7. Description of document versions