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 Z88P. 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 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 (must be 0 here !)
Plate 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 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 in addition:
area 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!