Bolted union

[Alejandre]

Hello everyone

Many days ago, I was trying to reproduce an analysis that was made with ANSYS about a bolted union, basically a base and a column(image1), and finally I got some results that are really close.

Mode ANSYS(Hz) ABAQUS(Hz)

1 206.48 205.6

2 208.08 206.38

3 434.53 408.23

4 662.62 691.48

5 1146.7 1124.6

6 1155 1128.9


I got those results due the post

http://www.eng-tips.com/viewthread.cfm?qid=295074(Prestressed

bolt with contact). I followed the post about the bolted union, and some questions came to me about some variables that were used. The first question is in relation to the image_2. The analysis used three constrains, between the bar and the base, the bar and the bolt, and the flange of the bolt and the base, but there is no constrain for the body of the bolt and the base. If you see at the image, there is an interference with the base and the bold, is this a normal behavior?, or what kind of constrain I must used to avoid this interference, because in the analysis such constrain does not exist!, or it is totally irrelevant?


The second question is, why do you chose Lagrange Multiplier?, because when I was using Penalty the results were really far from the ANSYS´s results.


The third question is: If you see there are two modes that are really close each other, Can you consider those modes like only one?


Thank you,

I hope someone help me to clarify this ideas.

 

[Alejandre]

Sorry guys, here is the image_1

 

[Alejandre]

And image_2...Sorry, my mistake

 

[rstupplebeen]

1. I am not sure what you are asking. Please provide 1 image with text on it.
2. My guess is that similar results were obtained because that is what Ansys is using also. I would check the Ansys model.
3. View the deformed geometry in the end what mode number it is isn't important it is the frequency that it occurs at.

I hope this helps.


Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/