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# Bolt calculation according to VDI 22303

## Bolt calculation according to VDI 2230

(OP)
Hello colleagues

Is there anybody famillar with VDI 2230 standard and calculations?

I must perform calculations of bolted joints and I am little bit confused with some points of mentioned VDI... i.e. How to include influence of special type of washer (Nordlock, Schnorr, Helical spring washer, etc.) and special type of nut (Flowtrap by Flowdrill, Riveted nut - RIVNUT, etc.)
Have you any tips for friction coefficent of powder coating - powder coating, powder coating - Zinc coating?

Scheme of bolted joint attached

Thank you and have a nice day

### RE: Bolt calculation according to VDI 2230

The variations that you have listed for washers and nuts are outside of the scope for VDI because they will be changing the effective spring rate of the joint. The nuts that you have listed are not intended, nor will they be effective for structural use where the fastener is intended to act as an elastic member. Both of your listed nuts are intended for use in non-structural joints; VDI is targeted to calculate the behavior of structural type joints.
Your best option is to conduct some torque vs. tension tests using a force washer or ultrasonic bolt gage.

### RE: Bolt calculation according to VDI 2230

Agree with Screwman1. Regarding friction coefficient, I think it is conservative to assume 0.1 for two surfaces with polymeric powder coating.

### RE: Bolt calculation according to VDI 2230

(OP)
Thank's for responses.
This look like a problem, because our customers requier calculations according to VDI and they want using mentioned special washer to avoid self-opeing.
Is anybody able to check my excel sheet with VDI "algorithm"? Because I'm not sure if equations and steps are used right.

Problem - If I want to a special type of washer, I cannot perform calculations according to VDI, because they are out of range VDI.
Solution - Replacing of special washers to ordinary could be simplification for calculation, right?

### RE: Bolt calculation according to VDI 2230

Yes, you can simplify your washer and nut to do the calculation.

### RE: Bolt calculation according to VDI 2230

The problem that I see with those nuts is that neither of them are at all structural and they will yield long before the bolt is loading to anything approaching capacity. The Nordlock or Schnorr washers will help hold the under-tensioned joint together, but the helical washer will be pretty much useless except to make someone feel good.

### RE: Bolt calculation according to VDI 2230

I agree with Screwman1. The helical split lock washer is less than useless in that it drives up part count and makes the bolted joint "softer" with a lower natural frequency. Amazing, though, that GE Transportation and perhaps other GE divisions still use them!

Tunalover

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