Learning Forum

[Omar Youssef]

Hello,

I'm analyzing flanged bolted connections and I am confused whether the extracted moment reaction should be included, that is if bolts can carry bending stress Mc/I and if it should be added along with the tensile stress F/A. If so, what are the cases that it should be considered? Can someone shed light on this please? Thanks!

Assuming pretension is applied at the correct shank section and surface in which reactions are extracted from is a few elements away from preload.

Regards,

Omar

[Ashish Khemka]

Hi Omar,

 

Why do you want to include the extracted moment reaction? I am assuming that you are talking about the moment reactions extracted after the simulation. If this is the case then it will increase the load unnecessarily.

Regards,

Ashish Kumar

[Omar Youssef]

Hi Ashish,

 

Thanks for your reply! Well, the reason is to add up the bending stress. When I insert the Normal stress on a surface perpendicular to the cross section of the bolt, I can clearly see three regions (compression, average, tension) implying that there is bending stress, right? Also, I'm curious why you say it will unnecessarily increase the load? Is the moment resolved in terms of the reaction force? How is that moment reaction calculated? 

I have read a couple of studies that include this bending stress. Here's one: https://cds.cern.ch/record/2305674/files/CERN-THESIS-2018-006.pdf

As far as I understand, since the stiffness of the flange is much higher than that of the bolt, it will absorb most of this moment, that's why VDI 2230 does not include it. However, there is a bending stress contribution according to this study.

If you look at page 81 section title "5.4.9 S8: Extract Values from the FE-analysis" it says "Note that when extracting forces and moments from surfaces, the nodal forces for that surface are summarized. This is a potential source of error" What do they mean by summarized? Thanks!

 

Regards,

Omar

[Ashish Khemka]

Hi Omar, we are not allowed to download attachments. Can you please share the relevant snapshot? My thought was that you extract the moment reaction and then reapply the same in the analysis. But it looks like bending is taking place in the bolt along with the pretension. In reality we bolt parts together first. Based on this thought you can preload the bolt, lock it and then apply the bending load.

 

Regards,

Ashish Khemka