Learning Forum

[Christopher Adam]

Hi,

I am trying to analyse a non standard geometry bolt when a preload is applied to see at what load it will fail and evetually determine a suitable torque to prevent bolt failing on assembly. The bolt is a hollow banjo bolt with an M6 thread and 1mm pitch.

Due to its geometry i cannot apply standard hand calcs so hoped i could put a basic simulation together inspired by the paper "Finite element analysis of relationship between tightening torque and initial load of bolted connections"

Is it possible to simulate applying a torque and hence preload to the joint and analyse the bolt? my attempts to replicate the above paper have been nothing short of disasterous.

Even when i supress the model to just the bolt and apply a small displacement to replicate the bolt stretching by 0.1 mm, the stress results are up to extreme with values well into the 1000s of MPa. EDIT:stress reaction is now OK by fixing my materials and applying a cylinderical support with axial and tangential freedom. Still cannot figure out how to apply a working torque

 

 

 

[Aniket Chavan]

Are you using nonlinear material properties?

-Aniket

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[Christopher Adam]

I have changed materials and applied a cylinderical support and the bolt now at least behave's exactly how i would expect when applying a displacement or preload equivalent force.

I still can't figure out a way to determine torque though, will i need to model the physical threads or is there a way around this seeing as the threads are not the critical area on the bolt?