Design to not exceed bolt clamp load or proof load

[TeejT]

Totally disregarding safety or "fudge" factor... is a bolted joint to be designed such that:
1. The joint loading never exceeds the bolt CLAMP load? OR
2. The joint loading never exceeds the bolt PROOF load?

If the loading exceeds the clamp load then the bolt would be forced to elongate, and it should return to its original length as long as the loading is less than the proof load, BUT I see this being more of a problem than no elongation at all (designing for the joint loading to never exceed the CLAMP load).
Thanks!

 

[btrueblood]

Yes. I.e. both 1 and 2.

Details are in Shigley, Mechanical Engineering Design, among others.

 

[desertfox]

Hi TeejT

Try this site:-

http://www.roymech.co.uk/Useful_Tables/Screws/Preloading.html

desertfox