Problem in generation of 2d model

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  • Last Post 15 January 2019
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rrathishubham posted this 12 January 2019

Hello everyone, I'm new to ANSYS so please dont mind if this is a really silly one. I'm trying to generate a model of cooling tower using axisymmetric but the problem is that i dont know how to place it at a position to get a proper radius and revolve it around y axis. I have attached a screenshot of cooling tower in 3d but i want the same in 2d. Please help.

Attached Files

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peteroznewman posted this 12 January 2019

It's good to do an axisymmetric model when you can.

For structural problems, the axis-of-rotation is the Global Y axis. Keep the geometry on the +X side of the Y axis.

For fluids problems, the axis-of-rotation is the Global X axis. Keep the geometry on the +Y side of the X axis.

ANSYS provides two Geometry editors, the newer one is SpaceClaim. There are several tutorials on SpaceClaim in the Tutorials section of this site.  You should become a little skilled at SpaceClaim and learn how to sketch and make a surface.

Please describe what you want to simulate in some detail.

Regards,
Peter

rrathishubham posted this 12 January 2019

I want to simulate in structure. I have tried a lot of times to create a 2d model but I always get an error saying " No valid bodeis found for 2D analysis".

peteroznewman posted this 13 January 2019

You didn't say if you are using SpaceClaim or DesignModeler.

After you sketch a closed loop on the XY plane, you need to either:

1. In SpaceClaim: Click the Pull tool or click the 3D mode button or

2. In DesignModeler: Concept > Surfaces from Sketchs > Generate

In either case, you will end up with a surface. This is what you need before you try to transfer geometry into Mechanical.

Regards,
Peter

rrathishubham posted this 13 January 2019

Thankyou sir for your reply. But how do I specify the distance from y axis?

peteroznewman posted this 13 January 2019

It depends on whether you are using SpaceClaim or DesignModeler.

rrathishubham posted this 13 January 2019

I will be using design modeler

peteroznewman posted this 13 January 2019

In DesignModeler, you click on the Dimension tab, select Horizontal dimension and click on the line and the dotted line of the Y axis.

rrathishubham posted this 13 January 2019

Thankyou sir. Also sir, I want to create columns at the base of cooling tower at equal intervals. So how do I do that? I want columns at 20 degrees interval.

rrathishubham posted this 13 January 2019

Sir, I have prepared the model in Revit and exported it to autocad in dwg format further i exported it to ANSYS in .iges file. And when I try to open mechanical, it says no valid bodies found.

peteroznewman posted this 14 January 2019

When you add columns at 20 degree intervals, that's not axisymmetric geometry, now it is a 3D model.

A 3D model can be built from a surface of revolution, plus surfaces to represent the columns.

I expect the iges file only had curves and no surfaces. Create surfaces and try to open that in Mechanical.

rrathishubham posted this 14 January 2019

Sir, it would be very difficult for me to make the model in ANSYS because that thickness of cooling tower varies at every 2.5m and it has a height of 175m. Also it has varying radius at every 2.5m interval.

peteroznewman posted this 14 January 2019

Do you have a drawing that calls out the thickness and radius as a function of height?

Please also reply with the load you wanted to apply to the cooling tower, was it only gravity?

I recommend you finish the 2D axisymmetric model before you add in the columns.

Then you can start a New Discussion for the 3D model.

rrathishubham posted this 14 January 2019

Yes, i have the drawing that calls out thickness and radius as function of height. Loads to be applied on cooling tower: gravity, wind, seismic

peteroznewman posted this 14 January 2019

Only gravity is an axisymmetric load.  Wind and seismic are not.

I recommend you finish the 2D axisymmetric model with just gravity to build some skill with ANSYS.

Please share the details of the thickness and radius as a function of height.  You can insert an image into your reply of either sections of the drawing or a table.  You can also attach files after you post your reply. Put whatever file you have into a zip file and attach the zip file.

rrathishubham posted this 14 January 2019

Sir, I'm not able to attach the files, can i get your mail id or something where i can send you the files??

peteroznewman posted this 14 January 2019

Do you have a zip file?

What is the file size?

When you click on the Attach button, Browse to the zip file and click Upload.

You will see the file upload. Please try again and describe in detail what happens if it does not attach.

rrathishubham posted this 14 January 2019

Its a zip file and the file size is 5.36 MB. When I select files and try to upload them, it shows 100% uploaded and it redirects me to same page and the files are not uploaded over there.

peteroznewman posted this 14 January 2019

Create three columns of numbers in a spreadsheet. Copy the three columns out of the spreadsheet and paste into Notepad. Format a line as Preformatted on the pull down in the toolbar. Copy all the lines out of Notepad and paste into that Preformatted line as shown below, except you will have 71 rows. 

height(m)  radius(m)  thickness(m)
0   20  1
2.5 19.5    1
5   19  1
7.5 18.5    0.95
10  18  0.95

 Alternatively, if you File, Save As the spreadsheet as a Text file and if the file has a .txt file extension, that is another allowed file extension for attaching files to replies. I know you were able to attach a .jpg file at the beginning. You can try to attach a .txt file now.

rrathishubham posted this 14 January 2019

Sir, details of geometry are attached in text format. 

Attached Files

peteroznewman posted this 14 January 2019

After you Reply, look at the buttons on the page and an Attach button appears. You have used that above. That is correct.  The problem with the file you attached is that it is empty.

If you copy text out of Notepad, you can paste it directly into the Reply window where you are typing. That is what I did. Try that.

rrathishubham posted this 14 January 2019

Note: Cooling tower starts from a height of 9.17m from ground as columns has a height of 9.17m 

height from ground (m) radius (m)  thickness (m)       
9.17    58.71998481 1.05        
10  58.45077875 1.044153913     
12.5    57.64576787 1.032       
15  56.84976984 1.031590909     
17.5    56.06308598 1.031162791     
20  55.28602742 1.030714286     
22.5    54.51891525 1.030243902     
25  53.7620806  1.02975     
27.5    53.01586474 1.029230769     
30  52.28061906 1.028684211     
32.5    51.55670517 1.028108108     
35  50.84449475 1.0275      
37.5    50.14436954 1.026857143     
40  49.45672111 1.026176471     
42.5    48.78195074 1.025454545     
45  48.12046904 1.0246875       
47.5    47.4726957  1.023870968     
50  46.83905899 1.023       
52.5    46.21999524 1.022068966     
55  45.61594831 1.021071429     
57.5    45.02736878 1.02        
60  44.45471322 1.018846154     
62.5    43.89844326 1.0176      
65  43.35902455 1.01625     
67.5    42.83692562 1.014782609     
70  42.33261666 1.013181818     
72.5    41.84656813 1.011428571     
75  41.37924925 1.0095      
77.5    40.93112648 1.007368421     
80  40.50266173 1.005       
82.5    40.09431064 1.002352941     
85  39.70652064 0.999375        
87.5    39.33972898 0.996       
90  38.99436075 0.992142857     
92.5    38.67082672 0.987692308     
95  38.3695213  0.9825      
97.5    38.09082036 0.976363636     
100 37.83507916 0.969       
102.5   37.60263028 0.96        
105 37.3937816  0.94875     
107.5   37.20881436 0.934285714     
110 37.04798141 0.915       
112.5   36.9115055  0.888       
115 36.79957782 0.8475      
117.5   36.71235664 0.78        
120 36.64996625 0.645       
122.5   36.61249606 0.24        
125 36.6    0.24        
127.5   36.61220718 0.237938144     
130 36.64589883 0.237826087     
132.5   36.6949721  0.237701149     
135 36.75396376 0.237560976     
137.5   36.81920808 0.237402597     
140 36.88846925 0.237222222     
142.5   36.96039863 0.237014925     
145 37.03416464 0.236774194     
147.5   37.10923758 0.236491228     
150 37.18526839 0.236153846     
152.5   37.26201957 0.235744681     
155 37.33932479 0.235238095     
157.5   37.41706451 0.234594595     
160 37.49515085 0.23375     
162.5   37.57351785 0.232592593     
165 37.65211516 0.230909091     
167.5   37.73090367 0.228235294     
170 37.80985258 0.223333333     
172.5   37.88893734 0.211428571     
175 37.96813811 0.2     
176 37.99984718 0.2

rrathishubham posted this 14 January 2019

Note: Cooling tower starts from a height of 9.17m from ground as columns has a height of 9.17m 

height from ground (m) radius (m) thickness (m)

9.17 58.71998481 1.05

10 58.45077875 1.044153913

12.5 57.64576787 1.032

15 56.84976984 1.031590909

17.5 56.06308598 1.031162791

20 55.28602742 1.030714286

22.5 54.51891525 1.030243902

25 53.7620806 1.02975

27.5 53.01586474 1.029230769

30 52.28061906 1.028684211

32.5 51.55670517 1.028108108

35 50.84449475 1.0275

37.5 50.14436954 1.026857143

40 49.45672111 1.026176471

42.5 48.78195074 1.025454545

45 48.12046904 1.0246875

47.5 47.4726957 1.023870968

50 46.83905899 1.023

52.5 46.21999524 1.022068966

55 45.61594831 1.021071429

57.5 45.02736878 1.02

60 44.45471322 1.018846154

62.5 43.89844326 1.0176

65 43.35902455 1.01625

67.5 42.83692562 1.014782609

70 42.33261666 1.013181818

72.5 41.84656813 1.011428571

75 41.37924925 1.0095

77.5 40.93112648 1.007368421

80 40.50266173 1.005

82.5 40.09431064 1.002352941

85 39.70652064 0.999375

87.5 39.33972898 0.996

90 38.99436075 0.992142857

92.5 38.67082672 0.987692308

95 38.3695213 0.9825

97.5 38.09082036 0.976363636

100 37.83507916 0.969

102.5 37.60263028 0.96

105 37.3937816 0.94875

107.5 37.20881436 0.934285714

110 37.04798141 0.915

112.5 36.9115055 0.888

115 36.79957782 0.8475

117.5 36.71235664 0.78

120 36.64996625 0.645

122.5 36.61249606 0.24

125 36.6 0.24

127.5 36.61220718 0.237938144

130 36.64589883 0.237826087

132.5 36.6949721 0.237701149

135 36.75396376 0.237560976

137.5 36.81920808 0.237402597

140 36.88846925 0.237222222

142.5 36.96039863 0.237014925

145 37.03416464 0.236774194

147.5 37.10923758 0.236491228

150 37.18526839 0.236153846

152.5 37.26201957 0.235744681

155 37.33932479 0.235238095

157.5 37.41706451 0.234594595

160 37.49515085 0.23375

162.5 37.57351785 0.232592593

165 37.65211516 0.230909091

167.5 37.73090367 0.228235294

170 37.80985258 0.223333333

172.5 37.88893734 0.211428571

175 37.96813811 0.2

176 37.99984718 0.2

peteroznewman posted this 14 January 2019

What version of ANSYS are you using:  18.2  19.2  other?

rrathishubham posted this 14 January 2019

I'm using version 18.1

peteroznewman posted this 14 January 2019

Here is the plan. Take the spreadsheet and make two tabs, one for the inner surface, one for the outer surface. On the tab for the inner surface, delete the Thickness column. Cut the Radius column and paste it in front of the Height column. Now the first column is the X coordinate, the second column is the Y coordinate. Fill the third column with 0.0 for the Z coordinate.

On the second tab, in the fourth column, add the radius to the thickness to make the Y coordinate of the outer surface. Cut that column and Paste Special (Values) in front of column A to be the X coordinate. The height is the Y coordinate and insert a column of 0.0 for the Z coordinate. Delete the other rows.

Next you have to format those two tabs into the 3D Curve data format that DesignModeler requires.

Once you have a text file with the data in the correct format, you start a new Workbench file. RMB on the Geometry cell and get the Properties.  You must set the Analysis Type to 2D before you open DesignModeler.

In DesignModeler, Concept, 3D Curve. Definition > From Coordinates File. Then pick the inner surface file.  Repeat for the outer surface file.

Finally, make a sketch that uses those two 3D curves and two lines to close off the cross-sectional surface that is the geometry that can be meshed to perform an axisymmetric model.

Alternatively, you could put the inner and outer coordinates in one file and define a closed 3D line and you wouldn't have to sketch the two lines.

rrathishubham posted this 14 January 2019

Thankyou so much for your reply. I'll revert back once i create the geometry. Once again thankyou sir, thanks a lot.

rrathishubham posted this 14 January 2019

Sir, I was able to import the file and it created the curve as I wanted but could you please tell me that how do I create closed geometry? I even read the link you provided but I didn't understand that what should be the format for closed geometry and in the last row where shall I put 1 and 0 to close geometry.

peteroznewman posted this 14 January 2019

Forget about the closed curve.

You can have four groups in a single text file.

Group 1 can be the inner curve from the bottom to the top.

Group 2 can be from the inner top to the outer top (two points).

Group 3 can be the outer curve from top to bottom (reverse sort the height).

Group 4 can be from the outer bottom to the inner bottom (two points).

I think you will be able to select these four curves to make a surface.

rrathishubham posted this 15 January 2019

Sir, I made the geometry using 4 groups and later using "Surface from Edges", I created surface. Is it correct? And once I take the geometry into mechanical tab, I cant see any option to revolve the geometry.

rrathishubham posted this 15 January 2019

Also, can i put reinforcement in 2D model? Or do I need to model it in 3D? If I can put the reinforcement in 2D model, then how can I put?

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