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Modeling an assembly with a bolt,nut, and three elements in between (Nastran NX12)

Experimenter
Experimenter

Hello,

This is my first post in this or any FAE forum and I apologize if this becomes a correction of many minor details within my model. Neverthaless I hope people can point me towards any angle that would improve my FEM skills and solve this issue as robostly as possible.

I am currently attempting to model a  "fixture" that must support an actuator within it for the tuning of such actuator. The actuator is attached to the fixture by means of a rod end as seen below. There are many easily characterisable input loads that we have planned for this fixture. Modelling the fixture properly is the issue.

In the pictures below it becomes evident that my issue is that the only method of modelling a bolt connection in NX I have found is that of assuming its a 1d element and using spider mesh elements to model the nut and head. For the 2 elements simulations online this is enough. For me, The load is applied to a third element that rests in the bolt, I have not been able to find any  contact type that woulda llow me to model this witht the 1d element. This in turn has made my Natran solutions unreliable.

Is there another way to model the bolts as toa llow contacts with teh bolts and their preload? I have not found anything in such respect.

 

[img]https://i.imgur.com/eaMnYnb.png[/img]

2 REPLIES 2

Re: Modeling an assembly with a bolt,nut, and three elements in between (Nastran NX12)

Phenom
Phenom

Good looking model!  I would however brick mesh anything possible to brick mesh, you'd get a model that runs much faster and give you equivalent results, if not better.

 

I don't think NX Nastran is able to do beam to solid contact like MSC Nastran does (hint to Siemens PD, please make it happen Smiley Happy ).  BUT, bolts can absolutely be modeled with solid elements and preload applied to them too.  

Re: Modeling an assembly with a bolt,nut, and three elements in between (Nastran NX12)

Experimenter
Experimenter

Thanks Tentechllc!

I appreciate the advice. Do you mean then to have the modeled bolt meshed and set to contacts with the rest of the assembly. If so, could you explain or point out any guidlines on how to set up the loads for doing so? In which surfaces specifically and what kind of loads.

Thanks!