Sidebar
This is an old revision of the document!
Table of Contents
PLXLS
Description
Plane state or axisymmetrical element
For the axisymmetrical element, the axis of symmetry must be the Y axis.
The element is defined by 3, 4, 6, or 8 nodes (see Input file).
For the generalised plane state, 8 nodes of the plane must be defined; the ninth is automatically the last one of the NODES section.
The 4 nodes elements are not of very good quality:
- With 1 integration point, hourglass modes may appear
- With 4 integration points, locking (shear or volumetric) can occur.
Element type: 9
Implemented by: J.P. Radu & J.D. Barnichon (1996)
Files
Prepro: PLXLSA.F
Lagamine: PLXLSB.F
Input file
Title
| (A5) | |
|---|---|
| TITLE | “PLXLS” in columns 1 to 5 |
Control
| (3I5) | |
|---|---|
| NELEM | Number of elements |
| ISPMAS | 0 = nothing |
| 1 = if density taken into account (if and only if NTANA=-1) | |
| INSIG | 0 if no initial stresses |
| 1 or 2 if initial stresses | |
| 3 or 4 if residual stresses in cylinder | |
Density (for dynamic analysis) - Only if ISPMAS = 1
| (1G10.0) | |
|---|---|
| SPEMAS | Density |
Initial stresses - Only if INSIG > 0
If INSIG = 1 or 2
If INSIG=1: $\sigma_y=\sigma_{y0}+yd\sigma_{y}$
If INSIG=2: $\sigma_y=min(\sigma_{y0}+yd\sigma_y,0)$
| (4G10.0) | |
|---|---|
| SIGY0 | $\sigma_{y0}$ effective stress $\sigma_y$ at the axes origin |
| DSIGY | Effective stress gradient along Y axis |
| AK0X | $k_0$ ratio $\sigma_x/\sigma_y$ |
| AK0Z | $k_0$ ratio $\sigma_z/\sigma_y$ (if AK0Z=0, AK0Z=AK0X) |
Definition of the elements
| (3I5/8I5) | |
|---|---|
| NNODE | Number of nodes: 3, 4, 6, or 8 |
| NINTE | Number of integration points: 1, 3, 4, 7, or 9 |
| LMATE | Material |
| NODES(NNODE) | List of nodes |
Results
The mechanical Cauchy stresses are ordered as: $\sigma_x, \sigma_y, \tau_{xy}, \sigma_z$. These stresses are expressed in the global axis system.
