Learning Forum

[Tim Dukes]

Hi Support, 

Few questions on bolts in the 2022R2 release.

The new Assign tool allows you to apply bolts to your models automatically. 

In the below image it mentions 'Automatic pre tensioning' what does this mean? 

If I then add a pre Bolt preload is this automatic pre tensioning ignored? Just wondering if it will then overtighten if it is not?

With the Bolt Pre Load you can specify a 'Torque' value. I presume this is the torque required to tighten the bolt?

It mentions torque co-efficient is this friction co-efficient and the table in this document could be used as a rough guide - (Link removed due to Forum posting guidelines)

If you have used the Bolt tool to assign bolts it automatically allows you to search for similar holes. 

In the image circled it says you can do this for adding preloads?

Edit: Worked this out all the bolts can be selected in the structure tree to allow preload to be applied to all without having to go through manually one by one.

Last question is on washers. When using the bolt tool it gives a defaults washer 'head' diameter which cannot be changed. If I was using a larger washer I may see different results in reality as a load maybe more spread. Do you have any thoughts on this or is that even if we could change the size it would not effect the results seen?

 

[Subashni Ravichandran]

Hello Tim Dukes

Bolt preload can be applied using the preload tool as shown in image below. 

Although let me check back with the team on more clarity on the statement as seen in your first image. 

While defining the bolt, the SAE standard bolt heads are predicted automatically based on the size in the geometry and defined accordingly. 
Let me check with the team if a custom size can be defined here. 

[Tim Dukes]

Hi  Subashni look forward to hearing what they say.

 

Further to this if I have a symmetry plane that is going through a bolt as in image below, I see larger forces than I would expect. 

 

Is there any thing you would suggest in this use case or is just you wouldn't suggest using symmetry planes through a bolted area?

 

 

No Symmetry plane

[Tim Dukes]

Hi Subashni just wondering if you had any feedback on this?

[Subashni Ravichandran]

Hello Tim Dukes

I checked back and I can confirm that the document photo you have shared refers to the automatically created beam element and the pre-tension needs to be applied manually. 

Ans regarding the symmetry condition across the bolt, as bolt is a beam element here, I'm not quite sure if it is good idea to apply a symmetry condition across it. 
Although I will need to test and investigate how symmetry would act here. 

[Rob Shropshire]

Subashni did you manage to investigate how symmetry would act here? Using a symmetry condition was speeding up the simulation for the customer, the alternative being mirroring the part which will take longer to run.

[Subashni Ravichandran]

Rob Shropshire  Tim Dukes

I checked back with the development team and they confirm that the symmetry condition applies to the solid faces, but not to the idealized bolt. As a workaround, you could create or select a bolt with 1/2 the stiffness of the original bolt and apply 1/2 the pretension load to the bolt on the symmetry plane.

[Rob Shropshire]

Subashni - thanks for your response. Much appreciated.