Reversing Fastener Head

[sabedi]

Hello people, i have an urgent request for some info on an issue i am dealing with. I am trying to find out the consequences of reversing the fastener head, i.e. flipping the fastener head with the nut. If its a tension application, what sort of loss of strength am i looking at, any books or references that talk about this.
Thx

 

[wes616]

RE Peterson, Stress Consentration Factors (1974)

Regarding Pre-loaded bolts in pure tension, under dynamic loading conditions:

15% of failures occur at the fillet under the bolt head, 20% occur at the end of the threads on the shank, and 65% occur at the nut face.

What type of fasteners are you using, and under what loading conditions?

Wes C.
------------------------------
Light travels faster than sound. That's why some people appear bright until you hear them speak.

 

[sabedi]

Thanks for the reply. It is a nas6606 fastener, and it is a fatigue application. I will look into the Peterson book. Any further info will be appreciated.
Thnx!

 

[MintJulep]

I don't recall any text where the joint design chapter includes a factor for this.

I can't see how it would matter in a properly designed joint.

 

[yates]

There is asolutely no difference in a tension bolt application, provided the substrate holes are adapted (i.e.sufficient chamfer or diametral clearance to avoid interference between hole edge and bolt underhead fillet radius)

 

[Lcubed]

If the exchange of nut and bolt head causes you to tighten the bolt head rather than the nut, there will be a change in the torque-vs-tension relationship. This is covered in some of the fastener books, and probably on-line.

 

[yates]

Lcubed has it right. I forgot to point out this oft neglected fact. I thought that if someone wanted to reverse the heads, it could only be to improve accessibility in order to tighten the nut (the correct way of tightening a nut/bolt combination). I can't really see any other valid reason for wanting to reverse heads.

 

[rerig]

It also depends on the application. Most Bolt heads are either on the top surface or Inboard. If the nut comes off the bolt won't just fall out of the hole.
Old school this, but even a small factor of safety still counts.