Definition
Based on mechanics of continuum, a three dimensional solid can be classified in a given category. For a solid with dimensions R, L and t, with t being the thickness, L is the working direction and R is the curvature radius, write:
| • | if L/t > 20 and R/t > 20: Thin shell assumptions are valid (Kirchhoff or Mindlin shell models) |
| • | if 10 < L/t < 20 and 10 < R/t < 20: Moderately thick shell (Mindlin model) |
| • | if 4 < L/t < 10 and 4 < R/t < 1: Thick shell |
| • | if L/t < 4 or R/t < 4: Solids |
An adapted finite element mesh is then applied to each case:
| • | Shell theory: 2D mesh of the mid-surface |
| • | Thick shell: 3D mesh with constant normal stress assumption |
| • | Solids: 3D mesh without constant normal stress assumption |
In RADIOSS all of these formulations are available. For a given mesh, several kinds of formulations may be available based on:
| • | the number of integration points |
| • | the stress updating method |
| • | large or small strain assumption |
| • | plasticity options for necking and material law integration |
| • | type of element and hourglass formulation |
