3.3 MESH
GENERATOR INPUT FILE Z88NI.TXT
The layout of Z88NI.TXT is
very similar to the layout of Z88I1.TXT, the input file for the FE
processor: Only the &- labeled data is required in addition. Cause:
Z88NI.TXT can serve the plot program Z88O. Moreover, Z88NI.TXT can be copied
to the name Z88I1.TXT and therefore be used to feed the FE processor
with a
very rough structure for very first checks and results. Mind the
following
formats:
[Long] = 4
bytes or 8 bytes integer number
[Double] = 8 bytes floating point number,
alternatively with or without point
[Character] = A letter
1st input group, i. e.
first line, contains:
Dimension of the
structure (2 or 3)
Number of nodes of the super structure
Number of super-elements
Number of degrees of freedom
Number of material information lines
Coordinate flag KFLAG (0 or 1)
Beam flag IBFLAG (must be 0 here !)
Plate flag IPFLAG (0 or 1)
Surface and pressure loads flag (0 or 1)
& Trap radius flag NIFLAG (0 or 1)
Write all numbers into a
line, separate at least by one blank respectively. All numbers here of
the type
[Long].
Explanation KFLAG:
At input of 0 the coordinates are expected cartesian while at input of
1 polar
or cylindrical coordinates are expected. The latter are then converted
into
cartesian coordinates and thereupon stored in this form in Z88I1.TXT.
Caution:
The axially symmetric elements No.8 and 12 positively expect
cylindrical
coordinates, set KFLAG to 0 here !
Explanation IPFLAG:
If Plates No.20 appear in the structure, then set
plate flag IPFLAG to 1, otherwise it must be 0.
Explanation IQFLAG:
You may set here IQFLAG=1 as a reminder
if you plan to define a surface
and pressure loads file Z88I5.TXT. However,
IQFLAG has
no effect for the mesh generator.
Explanation NIFLAG:
In order to identify already defined nodes the mesh generator needs a
trap
radius. The defaults are 0.01 for for EPSX, EPSY and EPSZ if NIFLAG is
0. These
values can be modified at extremely small or large structures. To
initiate this
change, set NIFLAG to 1. The new trap radiuses of EPSX, EPSY and EPSZ
are then
defined in Z88NI.TXT as the 6th input group.
Example: Super-structure 2-dimensional with
37 nodes, 7 super elements, 74 degrees of freedom, one material
information
line. Cartesian coordinates, no beams (anyway forbidden in the mesh
generator
file), trap radius default value. Thus
2 37 7 74 1 0 0 0 0
2nd input group,
starting in line 2, contains:
Coordinates, one line per node.
Node number, strictly
increasing [Long]
Number of the degrees of freedom for this node [Long]
X-coordinate or, if KFLAG is 1, R- coordinate [Double]
Y-coordinate or, if KFLAG is 1, PHI-coordinate [Double]
Z-coordinate or, if KFLAG is 1, Z-coordinate [Double]
The Z coordinate can be
skipped at 2-dimensional structures. Enter angles PHI in radian.
Write all numbers into a line,
separate at least by one blank respectively.
Example: The node no.8 has 3 degrees of
freedom and the coordinates X = 112.45, Y = 0. , Z = 56.75. Thus: 8
3 112.45
0. 56.75
3rd input group,
starting after last node, contains:
Coincidence, two
lines for every finite element
1st line:
Element number, strictly ascending
Super-element type (7,8,10,11,12,20) [Long]
Write all numbers into a
line, separate at least by one blank respectively. All numbers here of
the type
[Long].
2nd line: Depending on
element type
1st node number for coincidence
2nd node number for coincidence
.....
20th node number for coincidence
Write all numbers into a
line, separate at least by one blank respectively. All numbers here of
the type
[Long].
Example: An Isoparametric Serendipity Plane Stress
Element No.7 has element
number 23. The
coincidence has the global nodes 14, 8, 17, 20, 38, 51, 55, 34 (locally
these
are the nodes 1-2-3-4-5-6-7-8, see chapter 4.7) . Thus resulting in two
lines:
23 7
14 8 17 20 38 51 55 34
4th input group,
starting after last element, contains:
Material
information, one line for each material information.
This material information
line starts with super-element no. inclusively [Long]
This material information line ends with super-element no.
inclusively
[Long]
Youngs's Modulus [Double]
Poisson's Ratio [Double]
Integration order (1, 2, 3 or 4) [Long]
Cross section value QPARA [Double]
... And if plates are
defined and IQFLAG=0, in addition:
surface load
Write all numbers into a
line, separate at least by one blank respectively. Beams and cams are forbidden in Z88NI.TXT.
Explanation cross
section value QPARA:
QPARA is element
type-dependent, e.g. for hexahedrons 0, for trusses the cross-sectional area, and for plane
stress elements the
thickness. Here are the mesh
generator-suitable elements:
Element No.1: Isoparametric
Hexahedrons 8 nodes
Element No.7: Isoparametric
Serendipity Plane Stress Element 8 nodes
Element No.8: Isoparametric
SerendipityTorus 8 nodes
Element No.10: Isoparametric
Serendipity Hexahedron 20 nodes
Element No.11: Isoparametric
Serendipity Plane Stress Element 12 nodes
Element No.12: Isoparametric
Serendipity Torus 12 nodes
Element No.20: Isoparametric
Serendipity Plate 8 nodes
Example: The structure has 34 super elements
No.7. The thicknesses are supposed to vary: Elements 1 to 11 thickness
10 mm,
elements 12 to 28 15 mm and elements 29 to 34 now 18 mm. Material
steel.
Integration order shall be 2. Thus three material information lines:
1 |
1 |
11 |
206000 |
0.3 |
2 |
10. |
2 |
12 |
28 |
206000 |
0.3 |
2 |
15. |
3 |
29 |
34 |
206000 |
0.3 |
2 |
18. |
& 5th input group,
starting after last material information line, contains:
The descriptive
details for the mesh generation process. 2 lines for every super
element.
1st line:
Super element no. [Long]
Finite element type( types 1,7,8,10,19,20) to be generated [Long]
2nd line:
Number of finite elements in local x direction [Long]
Type of subdivision of CMODE x [Character]
Number of finite elements in local y direction [Long]
Type of the subdivision CMODE y [Character]
Number of finite elements in local z direction [Long]
Type of the subdivision of CMODE z [Character]
The two values for Z are
skipped at 2-dimensional structures.
Explanations: CMODE can accept the following
values:
The local x-, y and z
axises are defined as follows:
See following sketch:
Example: Subdivide an Isoparametric
Serendipity Plane Stress
Element with 12 nodes
(Element No.11) into finite elements of type Isoparametric Serendipity Plane
Stress Element with 8 nodes (Element No.7). Subdivide in local x
direction three times equidistantly and subdivide 5 times increasing
geometrically in local y direction. The super element is supposed to
have the
number 31. Thus :
31 11
7 3 E 5 L (e or E for equidistant are equivalent)
& 6th input group,
optionally after the end of input group 5 :
Input group 6 is
required if NIFLAG was set to 1, i. e. the trap radiuses is upposed to
be
modified. 1 line :
Trap radius in global X
direction EPSX [Double]
Trap radius in global Y direction EPSY [Double]
Trap radius in global Z directionEPSZ [Double]
Skip the Z detail for
2-dimensionalen structures.
Example: The trap radiuses shall be set to
0.0000003 for X, Y and Z respectively. Thus :
0.0000003 0.0000003 0.0000003
This is effective only if
NIFLAG was set to 1 in the first input group!