Calculating Fastener Flexibility Values in Fastener Joints

Firstly, this is mainly a FEM & specifically Nastran question but since it is almost used exclusively used in Aerospace industry (?), I thought it would be more appropriate here rather in FEM.

I have a question on calculating fastener shear flexibility values for Nastran CBUSH element using Huth equation under a double shear setup.

I have created an image which hopefully will convey my question clearly:

So essentially my question is, does the industry use:

  1. n=1 (i.e. single shear condition) for each CBUSH element and consider thickness of one of the plates as ‘t/2’ during calculation of fastener shear flexibility using Huth equation?

  2. n=2 in Huth equation for each CBUSH element?


This 26 page document will help you to understand the basics.

“Rutman” fasteners. (pdf)

Above is a snippet.

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