How to estimate clamp loads for joints under cyclic loading 1

[adi1]

we are trying to do a small test study on one of the crank shafts bolts. we know that the operating condistions of the shaft produces a clyclic load of 5000 lbs on the joint.
how much (any rule of thumb?) preload should I use inorder the joint dosent come loose after a test.

anything over 5000 lbs should work? or any formula?

I know the more the better , but whats the minimum preload should I get in the joint to sustain a cyclic load of 5000 LBS.

Thnaks

 

[Tmoose]

joint geometry (small footprint) can result in "prying" forces greater than the nominal load.

http://www.motormeister.com/pics_2_99/mm_sketch.gif

 

[desertfox]

Hi adi1 (preload)

Look at this site:-

http://www.co-design.co.uk/dpg/bol/bol4.html

 

[Screwman]

Since this is a crankshaft application, I would think that it is likely that you would consider it to be a critical joint.
With that in mind you really need to have someone who understands bolted joint design take a look at this joint. It is much more complex than just saying that anything over 5,000 will work. There is a high likelyhood that that approach will lead to field failures. Don't mess with critical joints unless you really know what you are doing.

 

[adi1]

Thanks Desertfox and Screwman