Shell bolt model

[vga_23]

Hello,

I am trying to reproduce a shell bolt model like the one in "A global bolted joint model for finite element analysis of load distributions in multi-bolt composite joints".

This may be a similar question as the one in

https://www.eng-tips.com/viewthread.cfm?qid=492205,

but I still haven't found a solution. The paper mentions a contact tolerance of 10um, and clearance (but using finite sliding), so I can't fully understand what they meant and what options they used.

Additionally, the model runs just fine (although the solution is wrong, probably due to the contact definition and clearance) in a linear analysis. When nonlinearity is on, a bunch of negative eigenvalue warnings appear, but I can't seem to get rid of them.

Has anyone been successful in modelling anything like this?

Thank you!

 

[SWComposites]

I don't have the paper, and don't want to purchase it.
Why do you want/need such a detailed model using contact, clearance, etc?

 

[FEA way]

It would be best if you could just share your model (.cae file). If you can't do it then at least screenshots and descriptions of the important features (BCs, loads, interactions) will be needed.

 

[vga_23]

The geometry, BCs and constraints can be found in the previous thread:

https://files.engineering.com/getfi...09-62fb984f5c66&file=edgetosurfacecontact.PNG

I believe the problem may lie in the contact definition. They mention a 'contact tolerance' of 10 um and explore clearances of 10 um and 240 um, although there is no description of that. Since they are using finite sliding, I fixed "Specify tolerance for adjustment zone" to 0.01 and used an interference fit with a magnitude equal to the desired clearance. I'm not sure if this makes sense.

The eigenvalue problems appear using Nlgeom, and after plotting the load displacement curves, it seems like the stiffness of my model is also higher, though the material properties are the same as shown in the paper.

 

[FEA way]

(Strain-free) adjustment and interference fit are two different ways of treating initial overclosures in contact. Check the documentation chapter "Contact Initialization for Contact Pairs in Abaqus/Standard".