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# Compressive force on flange hole (coupling) - [Sanity check]

## Compressive force on flange hole (coupling) - [Sanity check]

(OP)
The system under review is a coupling with 4 bolts on flanges which is subject to a torque.

The goal is to calculate the maximum compressive/bearing stress on the flange hole(flange B) for a given torque. This stress should be compared to the flange material yield strength to ensure there is no deformation.

The approach taken was to calculate the tangential force from the torque and PCD of the bolts. Using the tangential force the compressive stress can be calculated from the projected area.

There is a radial element that has not been considered..... not sure if this is a mistake or not?

### RE: Compressive force on flange hole (coupling) - [Sanity check]

Hi lexiConvict

If you are looking for the bearing stress on the underside of the screw head then the area you should be considering is the diameter of the screw head minus the screw diameter and that will be quite a small area. Once you have that area then divide it into the axial force in the screw from
the torque specified, it is also worth pointing out that clamping loads from torque figures can be 25% plus or minus

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

### RE: Compressive force on flange hole (coupling) - [Sanity check]

Hi again

Looking further into your calculation you need the axial force for the bolt torque value, the force you have calculated is that from the torque value to which the coupling is subjected too. If you are looking for the compressive stress on the hole surface due to that torque value it’s around the 125Mpa, I have no idea where you get a bearing stress of 20Mpa from, nor do I know which is flange B because it’s not marked on the sketch.

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

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