Bolt Torque and Turn of Nut 4

[ColmClonkirk]

Hi All,

Quick question - A supplier is proposing a joint with a torque of 350Nm and 120 degrees rotation. What would the 120 Degree rotation equate to in torque or is there a simple equation be available?

Bolt is 10.9 grade and M30

Thanks!

 

[EdStainless]

The last time that installed head studs on an engine that went to yield the procedure torquing in three steps, and then two separate steps of turn-of-nut. We also had to mark the ends of the studs to assure that were not just twisting them (there were flats so that we could retain the stud).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[r6155]

@ EdStainless
There are several methods to hold a stud in a blind threaded hole and prevent it from twisting during the turn of the tensioning nut, with no flats at the end of the stud. Then the stud does not turn during removal.

Regards

 

[3DDave]

Once the stud is yielding in tension it may be more susceptible to torsion yield as well. Stopping the far end from turning won't prevent that. The presence of an additional feature is likely an expense they would avoid if it was not required.

 

[ColmClonkirk]

Thanks All for your comments and suggestions.
@desertfox, I will try your calculation again and see if I get similar load.
We can apply torque through electric torque gun, which also applies degrees rotation required.
But I believe the joint is poorly design and OEM is unwilling to provide some information, so I need to investigate it more.
We will likely unload stud, measure it using UT and torque it to correct setting, and measure with UT. Repeating this a few times to get accurate elongation will provide true load applied.
Will also recheck after certain time, to account for embedment.

 

[dik]

Do you have a picture of the joint?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[r6155]

Qualified personnel are required for the assembly of bolted joints, the same concept as for a welder.

Is this example a pressure-boundary body joints?

Regards

 

[Ng2020]

What kind of composite material?
You may want to consider retorquing after some time has elapsed, as some plastic matrices and sealants will flow a little resulting loss of initial preload in the short term.

 

[EdStainless]

If you go to yield remember that each fastener is a single use, and then discard.
When we were testing we would take a box of studs and gage everything that we could.
When we had a dozen that were very similar we would match grind them to a precise length.
That way we could test and not have to allow for differences in studs.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed