Structural prestress analysis on a rotating wheel fixed at center with rpm as load co

SaiPrasad Chowdavaram · September 24, 2020, 09:50

Hi all,

I am performing a prestress analysis on a rotating wheel which is fixed at center having given rom as load condition. I performed the same problem using 2d shell elements and 3d-solid elements separately with all the analysis details same materials, contacts . I observed high frequencies in 3d solid elements case.
Q. Is my observation is correct?
Q. If my observation is correct, what could be the reason for the high frequencies in Solid elements case compared to 2d shell
Q. How can we correlate both the results. Is there any defined explaination behind this.
Please let me know the reason . I thank all for the support. Expecting an explaination for the defined problem.
Thanku all

karachun · September 25, 2020, 07:06

This depends on many factors. Can you be more specific and show geometry, mesh, mesh order, BC. There are 1000 possibilities to make some errors.

SaiPrasad Chowdavaram · September 25, 2020, 10:03

Quote:

Originally Posted by karachun

This depends on many factors. Can you be more specific and show geometry, mesh, mesh order, BC. There are 1000 possibilities to make some errors.

Thanku for the reply but I cannot show u the geometry or mesh or related becoz it is my office problem being confidential . Hope u understand . I am really sorry

karachun · September 25, 2020, 15:14

Sorry, no info - no help.
In general if structure can be considered as thin walled and if it meshed, loaded and constrained in the right way then result modes will be almost the same. But "right way" is too complex to write it on a forum. There are many possibilities to make something wrong.
Therefore the answer to your first question is no, your observation isn`t correct. Modes should be similar.

SaiPrasad Chowdavaram · September 26, 2020, 04:56

Quote:

Originally Posted by karachun

Sorry, no info - no help.
In general if structure can be considered as thin walled and if it meshed, loaded and constrained in the right way then result modes will be almost the same. But "right way" is too complex to write it on a forum. There are many possibilities to make something wrong.
Therefore the answer to your first question is no, your observation isn`t correct. Modes should be similar.

I agree to ur point . Mode shapes are same . I observed that frequency numbers are high . Difference in frequency numbers between the shell and solid mesh is 2Hz

karachun · September 26, 2020, 10:23

Quote:

Originally Posted by SaiPrasad Chowdavaram

Difference in frequency numbers between the shell and solid mesh is 2Hz

What is the relative difference? What is frequency order: 10 Hz, 100Hz, 1000 Hz?

SaiPrasad Chowdavaram · September 27, 2020, 11:39

Quote:

Originally Posted by karachun

What is the relative difference? What is frequency order: 10 Hz, 100Hz, 1000 Hz?

First frequency in shell is around 14.5 Hz whereas in solid mesh it is around 16.5 Hz

karachun · September 28, 2020, 02:42

~15% relative error. It is not small but also not giant.
I can recommend to perform mesh convergence study - reduce alement size and recalculate model until mode frequencies and shapes stop changing.

September 24, 2020, 09:50	Structural prestress analysis on a rotating wheel fixed at center with rpm as load co	#1
SaiPrasad Chowdavaram New Member SaiPrasad Join Date: Dec 2017 Posts: 17 Rep Power: 8	Hi all, I am performing a prestress analysis on a rotating wheel which is fixed at center having given rom as load condition. I performed the same problem using 2d shell elements and 3d-solid elements separately with all the analysis details same materials, contacts . I observed high frequencies in 3d solid elements case. Q. Is my observation is correct? Q. If my observation is correct, what could be the reason for the high frequencies in Solid elements case compared to 2d shell Q. How can we correlate both the results. Is there any defined explaination behind this. Please let me know the reason . I thank all for the support. Expecting an explaination for the defined problem. Thanku all

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September 25, 2020, 07:06		#2
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	This depends on many factors. Can you be more specific and show geometry, mesh, mesh order, BC. There are 1000 possibilities to make some errors.

September 25, 2020, 15:14		#4
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	Sorry, no info - no help. In general if structure can be considered as thin walled and if it meshed, loaded and constrained in the right way then result modes will be almost the same. But "right way" is too complex to write it on a forum. There are many possibilities to make something wrong. Therefore the answer to your first question is no, your observation isn`t correct. Modes should be similar.

September 28, 2020, 02:42		#8
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	~15% relative error. It is not small but also not giant. I can recommend to perform mesh convergence study - reduce alement size and recalculate model until mode frequencies and shapes stop changing.