Element Discretisation

Question 1

2D elements

Answer 1

Linear:
Refers to the order variation of deformations over the element
- 3 node triangular
- 4 node quadratic

Quadratic:
Additional nodes at the mid-vertices the order variation of deformations over the element
- 6 node triangular
- 8 node quadratic

These arent recommended for soils since they are highly nonlinear

Question 2

3D elements

Answer 2

-4/10 node tetrahedral
-8/20 node hexahedral
-3 DoFs with displacements u,v,w with w added from 2D
* Defines the size of the problem in terms of the number of equations to be solved

Question 3

Mesh design considerations

Answer 3

-Appropriate approximation of geometry
-Curves approximated with quad. elements
-Material interface must be at element sides, same for material to be excavated
-Forces should be applied @ nodes
-Points of large delta sigma should have a large number of small elements, larger ones can be used away @ the boundaries
-Regular element shapes are advised