[Node Locations] [Elements] [Cyl & FP Element Type] [Shell Element] [FP Connection] [Spring Element]

 

NODE LOCATIONS:

First, it was necessary to recreate the cylinder in ANSYS. This begins with locating all of the nodes in the I-DEAS model and determining how the coordinate system information and locations are output from I-DEAS.

This data is simply output in the format of :

1st Line : Node Number - Export coord. sys. - Disp coord sys - Color
2nd Line : X location - Y location - Z location


Node_coords_only.txt

1 3 3 11
0.0000000000000000D+00 5.0888811234474182D-01 -1.3970000000000011D-01
2 3 3 11
0.0000000000000000D+00 5.0888811234474200D-01 -1.3096875000000007D-01
3 3 3 11
0.0000000000000000D+00 5.0888811234474200D-01 -1.2223750000000006D-01
4 3 3 11
0.0000000000000000D+00 5.0888811234474200D-01 -1.1350625000000003D-01
5 3 3 11
0.0000000000000000D+00 5.0888811234474182D-01 -1.0477499999999999D-01
6 3 3 11
9.9675075888928166D-03 5.0888811234474200D-01 -1.3934395857899755D-01
7 3 3 11
8.7206966053394729D-03 5.0888811234474182D-01 -1.2192602616319188D-01
8 3 3 11
7.4738856217861915D-03 5.0888811234474182D-01 -1.0450809374738616D-01
.
.
.

Corner_Node_loc_for_Ansys.txt


However, because the cylinder was built along the Y axis, the X and Z coordinates were grouped in the output file. I know this
because of the documentation and the file header. Knowing that the file was output using CS3 (Coordinate System Number 3)
I know what order the nodal location data is output.

Below is the header for the file, and from this we can decipher the note below that the nodes are ordered according to CS 3 (Y - Z - X)


2420
5
Cylinder
1 0 8
CS1
1.0000000000000000D+000 0.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 1.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 0.0000000000000000D+000 1.0000000000000000D+000
0.0000000000000000D+000 0.0000000000000000D+000 0.0000000000000000D+000
3 1 8
CS3
0.0000000000000000D+000 0.0000000000000000D+000 1.0000000000000000D+000
1.0000000000000000D+000 0.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 1.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 1.3010426069826053D-018 0.0000000000000000D+000
2 0 8
CS2
1.0000000000000000D+000 0.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 1.0000000000000000D+000 0.0000000000000000D+000
0.0000000000000000D+000 0.0000000000000000D+000 1.0000000000000000D+000
0.0000000000000000D+000 0.0000000000000000D+000 0.0000000000000000D+000
-1
-1
2411


Next a Matlab code was written to just re-arrange the coordinates for entry into ANSYS. This nodal data was then re-formatted for entry into ANSYS following
the format in table 1, below:

n
Node Number
X Location
Y Location
Z Location
n,
1,
-0.1397,
0,
0.50889
n,
3,
-0.12224,
0,
0.50889
n,
5,
-0.10477,
0,
0.50889
n,
n,
n,
n,
n,
6735,
0.047291,
-0.050828,
1.30E-18
n,
6736,
0.048686,
-0.037081,
1.30E-18

Table 1: ANSYS node format

This nodal information was inserted into the ANSYS Batch file to create the same nodes in an ANSYS model as were used to create the I-DEAS model. The nodes created by the ANSYS Batch file appeared as follows:

Figure 1: Cylinder Nodes

ELEMENTS:

Once all of the nodes are in place, it is necessary to mesh the cylinder with the same kind of elements at the same nodal locations.
This set of data is exported from I-DEAS in the format as follows:

Element Number - Element Type (eg. Shell, Bar, Spring) - Other information
Nodes associated with element


Element_Node_Numbers.txt

2017 95 4 2 7 8
6735 6842 6732 6773 6730 6843 6728 6846
2018 95
4 2 7 8
6736 6841 6735 6846 6728 6845 6733 6833
2019 121 5 2 8 2
1 1829
2020 121 5 2 8 2
3 1831
2021 121
5 2 8 2
1 6848
2152 136
15 0 8 2
194 6848
2153 136
15 0 8 2
9 6848

Element_and_nodes_for_ansys.txt

In the case of the shell elements, it is necessary to keep the nodes in the proper order, because they are meshed in a certain order (as seen below). For this reason it was necessary to make sure that ANSYS meshed these types of elements in the same order. If not we would have had to re-arrange the elements. Luckily, ANSYS handled these elements in a similar fashion, so there was no re-arranging necessary.

However, you may notice from the nodal location list above, that the node numbers progress 1, 3, 5, . . .etc.: This is because the ANSYS model was built with 4-noded area elements as apposed to the 8-noded area elements of the I-DEAS model. This was done in order to reduce the total degrees or freedom in the model and thereby the computing time.

The conversion from 8-Noded shells to 4-Noded (Matlab File Link) ones was performed as follows:

Figure 2: 8 node and 4 node shell elements

Cylinder and Face-plate Element Type

In the I-DEAS model, the above set of nodes makes up the corners of elements which represent the cylinder and face-plate. The same nodes were used to represent the same geometry in ANSYS. The type of element, in the Finite Element sense, had to be defined in ANSYS before actually constructing them. A set of 2-D Shell Elements was used and the following information was included in the ANSYS Batch file:


!-define-element-type-1---
et,1,shell43
!-element-Properties----
mp,ex,1,193.0532e9
mp,ey,1,193.0532e9
mp,ez,1,193.0532e9
mp,nuxy,1,0.3
mp,nuyz,1,0.3
mp,nuxy,1,0.3
mp,gxy,1,80.15504e9
mp,gyz,1,80.15504e9
mp,gxy,1,80.15504e9
R,1,0.0002,0.0002,0.0002,0.0002,,


This element has a planar geometry, a node at each corner, and 6 degrees of freedom at each node.

Shell Element Node Numbers

The element node numbers from the I-DEAS model were extracted and arranged in the following order:
(MATLAB Code Link)

Figure 3: 4 Node Elements

Figure 4: Whole Cylinder

We can now see that the planar elements form the geometry for the cylinder and the face-plate.

The next view shows half of the model, giving a more informative view of the geometry, the element mesh, and the planar nature of the elements:

Figure 5: 4 Node Element Mesh - Half Cylinder


Face-plate Connection Element Type

In the IDEAS model, a set of stiff 1-D bar (or Truss) Elements was used to simulate the rigid connection between the face-plate and the cylinder. Analogous Link Elements were used in the ANSYS model. Like the Shell Elements, this Element Type had to be set in ANSYS and the following information for these elements was included in the Batch file:


!-define-element-type-2---
et,2,link10
!-element-Properties----
mp,ex,2,1e20
mp,ex,3,1e5
R,2,0.0002


 

Figure 6: Rigid Bars

 

Spring Element Node Numbers

The final set of nodes used in the I-DEAS model, are meshed with a spring element. In a similar fashion to previous elements, the element node numbers were extracted from the I-DEAS model and arranged in the following order:


!-form-spring-elements---

type,2
mat,3
real,2

e,1,6848 !-element-2151---
e,194,6848
e,9,6848
e,177,6847
e,354,6847
e,169,6847



Spring Elements

The Spring Elements can be seen below:

Figure 7: Whole Cylinder With Springs

 

Final ANSYS Batch file without nodes or elements