Simulating a Screw joint

[Anonymous]

Hi everyone,

How can we simulate screw joint in autodesk mechanical... In 'CAD additions > generate bolt connection'  there is an option for bolted connection without nut and grounded bolt, can we use this? And the two parts joint by screw connection have to be surface contact or bonded. Also, do we have to set any contact beween the screw and parts to be joint?

Thanks

Siddharth

[AstroJohnPE · Accepted solution]

Hi Siddharth,

A screw would be simulated as a "bolt without a nut". (Now that I think of it, the wizard/dialog should be called a "fastener" instead of a "bolt", and "tight fit" should be "threaded".) In the section where you specify which surface numbers are the interior surface of the hole, you would click the "tight fit" checkbox next to the surfaces where the threads are located. This ties the bolt shank to each node on the surface, as if the bolt/screw threads are threaded into the surface. Please see the page "Bolts and other fasteners" in the online Help.

As for the type of contact between the parts, you set that based on how the parts interact in the real situation, or what ever type of contact is acceptable for the simulation. The contact between the parts is not affected by the bolt. And since you cannot define surface contact between a line element that is used for the bolt and the solid part, you cannot set that to be surface contact. 🙂 Your options are either free contact or bonded.

[Anonymous]

Hi John,

Thanks for sorting out my confusion. Your reply proven a great help for me.

Thanks and Regards,

Siddharth

[Anonymous]

Hi, I am working on an IGS solid assembly file for doing FEA on modal analysis and static analysis.

How do i simulate a screw fasterning to an igs imported file?? I tried using the bolt without nut function but it doent work when i click ok. i think you might know the anwer.

Regards,

Harsh. 

[Anonymous]

Hi Harsh,

I have not yet got a chance to work with IGS file. However, if the file is being opened properly and you are being able to set contact between the parts, then there must not be the problem in setting the screw joint. Can you explain what error are you getting? 

Regards,

Siddharth

[Anonymous]

I am not even able to click "ok" after choosing the bolt head contact
surface and the interiro hole surface.


the message is 'the bold wizard was unable to determine a hole from the
input surfaces. Check that the interior surfaces of the hole are correct.

I have attached a picture with this message also.

[AstroJohnPE]

Hi,

The picture did not come through for some reason. But the message is implying that the software cannot determine the centerline of the hole. (I think that is what it is saying.) It would help us if you could slice your model through the hole so that we can see what it looks like.

[Anonymous]

Hi I am having the same issue, same message. I am attaching a PDF where I explain how I selected the surfaces, hope you guys can help me.

Thank you,

Juan Alfonzo

[AstroJohnPE]

It's not possible for me to know what's going wrong from the images, so these are all guesses.

1. Ignore the message. If the bolt is created and it looks acceptable, it is acceptable.
2. Try a different mesh size.
3. What does part 5 surface 12 look like? Is it a cylindrical surface? Something else?
4. Otherwise, provide an archive of your model. Maybe someone can determine the problem and solution from having the actual model. See the post "Create, Post, or Provide an Archive of your model" for details.

I don't understand a couple of things in your attached images.

• In the second image, it shows lines for the bolt in the hole. Where did those lines come from? Had you already clicked the OK button to generate the bolt?
• The second image also shows that two surfaces had been added to define the inside of the hole. But the third image shows no surfaces listed. Is that just a display problem (the dialog needs to be refreshed to show the entries in the list box), or did the surfaces of the interior hole disappear?
• Also, the third image shows a bunch of lines in the hole, but different than the second image. It looks as if the bolt is connected to the nodes on the surface of the hole, as if the "tight fit" option was activated. What was created?

[Anonymous]

Hi AstroJohnPE,

Thanks for answering,

The images i attached are not so great I know, sorry about that. I ignored the messages and managed to create the connections (I think). I will attach the file with the parts in a separate post, in the mean time you can see what part5 and 12 look like.

When it asks for INTERIOR HOLE SURFACE(S) FOR ONE HOLE, Do I need to select the two cylindrical surfaces that the bolt is going to go thru? One of them is a clearance hole and the other one would the tapped hole, that is what I did and it seemed to work.

Please see attached file. Hopefully I can attach the whole assembly tomorrow or Monday, againg thanks for your help.

JA

[bryan_mcnatt]

AstroJohnPE, you need to get that change to the dialog/wizard you mentioned incorporated, pronto.