Bolt with MPC (washer) and Beam (shank) 2

[MegaStructures]

Hello,

I'm switching from FEMAP/NASTRAN to Abaqus and I'm used to being able to model a bolt shank with a beam element. In Abaqus it appears that you cannot directly draw a beam between MPC's and instead have to use a "connector section".

The connector section dialog does have a beam option; however, there is no way to input elastic properties, so I assume this is simply a rigid beam. What is the easiest way to get an elastic beam to use for a connector?

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[FEA way]

The easiest way to model a bolt with 1D elements in Abaqus is to create a wire between two reference point and assign proper section to it. Of course you also have to connect these RPs to the model with couplings or MPCs. Check the article titled "Modeling Bolted Connections with Abaqus FEA" on Simuleon’s blog post for the detailed description.

 

[MegaStructures]

Thanks for the reply FEA way! I have read that blog post by Simuleon and it is exactly what I would like to do; however, they don't show how they modeled the beam in place.

In FEMAP you can simply "draw" a beam by selecting two points in an assembly view. In Abaqus I can only draw a wire the interaction module, or part module, and I can only apply sections in a part view. How do I get to a view where I can see my reference points/wire that connects two separate parts and be able to assign a property?

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[MegaStructures]

More concisely. How do you apply a beam property to a wire in an assembly view?

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[FEA way]

For this article, they created a wire part first and assigned a beam section to it (like when you normally model a beam) and then placed it in the right spot of the assembly. Finally, they connected the beam's ends to the rest of the model using MPC constraint (type beam). They explain this in one of the comments under the article, but anyway - that's the only method if you want to use beam elements instead of connectors.

 

[MegaStructures]

Thanks FEA way. I was afraid that was the only way to do it. So far I have preferred Abaqus to FEMAP/NASTRAN, but the module concept can be a bit limiting in cases like this.

I really appreciate your help!

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[FEA way]

If you want to define multiple bolts this way, it’s rather easy to automate the whole process using Python scripting in Abaqus. You could even create your own plug-in or additional menu for this purpose.

 

[MegaStructures]

I would LOVE to be able to do that, but I'm not even sure where I would start!

I can picture how it could work, but I have no idea how to get it done. I'm picturing that you could define, in the assembly view, a start point, end point, and surfaces associated with each and the python script could create a new part, assign a property, place in the assembly view, and create MPC's.. How cool would that be!!

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[FEA way]

It’s definitely doable. The script would have to place instances of beam parts in proper locations in assembly and then it’s just a matter of connecting their ends to nearby faces/edges of the model using MPCs. The script could also change the circular beam profile radius for each part so that it fits in a particular hole.

If you are interested in Python scripting in Abaqus then, apart from studying the documentation (there are two chapters about scripting), it’s a good idea to model something in CAE first and then read the replay (rpy) file which contains commands necessary to recreate everything that was done in GUI.

 

[MegaStructures]

FEA way your advice worked great, I've modeled my bolts and have a working model. Do you have any tips to easily output the bolt (beam) forces for hand analysis?

Edit: Every bolt in the model is the same size. I would like to output a scalar value for maximum shear and tensile force in each bolt, rather than plot the entire force history of each bolt.

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[FEA way]

It’s actually easier with connectors but you can request output of section forces for beam elements.