PEM STUD Torque Calculation

[Ninja_Newyork]

I am using a PEM stud of size M6 on a aluminium sheet metal of 2mm thickness. PEM stud material is MS. I have used torque value of 8NM and I am expressing the stud pulling off from the aluminum sheet metal.
What Would the calculation to determine the required torque for this case. I dont want to relay on the PEM data, i would like to know the calculation to determine the required torque for this scenario ? Functionality is not critical it is just to hold this aluminum sheet metal to be in place, no external load.

 

[drawoh]

Ninja_Newyork,

The material is called up as "heat treated carbon steel". This does not leave us with yield/proof stresses. For regular carbon steel, I get a torque 4N.m, based on the tensile strength of the stud The tension force is around 10,000lb. According to their flyer, their torque-out could be as low as 7N.m, and their pull-out as low as 9000lb.

--
JHG

 

[MintJulep]

It would be helpful to know:
The specific type of stud.
The specific type and temper of the aluminum sheet.
The details of the connection.
The details of the failure that you experience.

With that, you should be able to figure things out - approximately. But frankly, it would be a lot of work, and not so useful because of the variability in the torque to tension relation.

It would be much simpler to install a bunch of studs and test them to failure. Then select the max torque that consistently doesn't result in pull out.

 

[Ninja_Newyork]

Material where the Pem is going to be install is aluminum 5052 their hardness is 63 HRB. Flush head pem GI and thir functionality is to hold two aluminium parts. We are torquing to 8 Nm on the nut. This gets pulled out ! What would be the reason.

 

[SWComposites]

Do you mean the head of the stud is being pulled thru the sheet? Before the stud rotates? Sounds like the sheet is too thin.
What is the head height? And sheet thickness?
Can you post a photo of the failure mode?

 

[desertfox]

Hi

Still not sure which stud we are looking at however I note on this reference that the aluminium sheet should be a maximum of 1.5mm thick and not 2mm. The torque you are using according to this reference are inside there set limits, so my question is are you torquing the nuts with or without lubricant because that could have a huge impact on the failure you are experiencing.

https://www.pemnet.com/eu/products/product-finder/hfh-m6-15zi/#installation-performance-data

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[MintJulep]

What would be the reason?

The holes in the sheet are too big before the studs are pressed.
The hole edge finish does not comply with PEM's recommendations (don't deburr).
The studs are not pressed properly.
Your torque wrench is not calibrated.
Your technicians don't stop turning with the wrench goes 'click'.
Your load path causes bending of the sheet, contributing to pull-through.
Your studs are counterfeits from China. There is no "GI" on the official PEM web site. All references to "GI" studs seem to be from China.

This guessing game is fun! Is there a prize for guessing right?

If not, how about some technical details.