4.11
PLANE STRESS ELEMENT NO.11 WITH 12 NODES
This is a curvilinear Serendipity
plane stress element with cubic shape functions. The transformation is
isoparametric. The integration is carried out numerically in both
axises
according to Gauss- Legendre. Thus, the integration order can be
selected in Z88I1.TXT in the material information lines. The
order 3 is mostly the best choice. This element calculates both
displacements
and stresses with outstanding precision. The integration order can be
chosen
again for the stress calculation. The stresses are calculated in the
corner
nodes (good for an overview) or calculated in the Gauss points
(substantially
more exactly). Because of its 24*24 element stiffness matrices the
element
No.11 needs a lot of memory and computing power. Pay attention to edge
loads
when using forces, cf. chapter 3.4. It is
easier to
enter edge loads via the surface and pressure loads file Z88I5.TXT.
Plane
Stress Elements No.7
can be generated by the net generator Z88N
from super elements Plane Stress Elements
No.11. Thus, the Plane Stress Element No.11 is well suited as super
element. But
Plane Stress Elements No.11 cannot be generated by the net generator
Z88N from
super elements Plane Stress Elements No.11.
Input:
CAD (see chapter 2.7.2): 1-5-6-2-7-8-3-9-10-4-11-12-1
Z88I1.TXT
> KFLAG for cartesian (0) or polar coordinates (1)
> IQFLAG=1 if edge loads for this element are filed in Z88I5.TXT
> 2 degrees of freedom for each node
> Element type is 11
> 12 nodes per element
> Cross-section parameter QPARA is
the element thickness
> Integration order INTORD per each
mat info line. 3 is usually good.
Z88I3.TXT
> Integration order INTORD: Basically, it is a good idea to
use the
same value as chosen in Z88I1.TXT , but different values are permitted
0 = Calculation of the stresses in the corner nodes
1,2,3,4 = Calculation of the stresses in the Gauss points
> KFLAG = 0: Calculation of SIGXX, SIGYY
and TAUXY
> KFLAG = 1: Additional calculation of SIGRR, SIGTT and TAURT
> Reduced stress flag
ISFLAG:
0 = no calculation of reduced
stresses
1 = von Mises stresses in the Gauss points ( INTORD not 0 !)
2 = principal stresses in the Gauss points (INTORD not 0!)
3 = Tresca stresses in the Gauss
points (INTORD not 0!)
This file is
optional and only used if in
addition to nodal forces edge loads applied onto element no.11:
>
Element number with surface and pressure load
>
Pressure, positive if poiting towards the
edge
>
Tangential shear, positive in local r
direction
> 2
corner nodes and 2 mid nodes of the
loaded surface
The local r
direction is defined by the nodes
1-2. The local nodes 1, 2, 3, 4 may differ from the local nodes 1, 2,
3, 4 used
for the coincidence.
Results:
Displacements ino X and Y.
Stresses: The stresses are calculated in the corner nodes or
Gauss
points and printed along with their locations. For KFLAG = 1 the radial
stresses SIGRR, the tangential stresses SIGTT and the accompanying
shear
stresses SIGRT are computed additionally (makes only sense if a
rotational-symmetric structure is available). For easier orientation
the
respective radiuses and angles of the nodes/points are printed.
Optional von
Mises stresses
Nodal forces in X and Y for each elementand each node.