axial connectors in series

[rph5g]

I would like to use two axial connectors in series. One will be a stop connector and one will be elastic. In fact, it's nearly exactly what's pictured in the manual (without the plasticity):

I am using this in compression (rather, I would like to). I have not been able to successfully keep the three nodes colinear. The mid-span node acts as a balljoint. I've tried kinematic coupling contraints though I'm foggy on their proper application. I've tried eliminating the rotational degree of freedom using an equation constraint and I've tried just applying a BC to the central node (constrain rotation DOF). For some reason I've only found scant information on this application online. In the ABAQUS user community I found a connector powerpoint that acknowledged that you risk creating unwanted balljoints, but the fix was not described in a way that I followed. I'm using CAE / ABQ 2022. Thank you.

 

[SWComposites]

why would you not use a beam element for the right hand part with non-linear material properties?

 

[rph5g]

Thanks for the reply. Yes, I suppose that I could use a beam or a spring with non-linear properties to serve in a similar fashion. I remain hopeful that I can use connector elements in series just like they picture in the manual. I like the idea of being able to stack the components together to get what I need. It would be super convenient if only I could get past the issue of how to properly constrain the middle node to allow the assembly to handle compression. Thanks again.

 

[FEA way]

Can you share the .inp or .cae file with the model in which there’s this undesirable behavior without constraints applied to the middle node ?

 

[rph5g]

Hi. Thanks for the response. The original model was pretty large so I tried to whittle it down to a couple of representative pieces. That didn't go as smoothly as I had hoped... Anyhow, the attached input deck shows some of the behavior that I'm fighting; it might be helpful to dial up the displacement magnification to see the center connector node go out of line. To be honest, it's not behaving like I had hoped in other aspects as well. I would expect to see some stresses develop in the "block" component of the assembly at the application point of the connector. Are there any pointers for a rock solid step-by-step connector recipe out there? "top dog engineer" has a good youtube video where he's using connectors as bolts, but I'd really value a more general tutorial. I feel like I go down a rabbit hole using CAE to create connectors; as I iterate I end up with unused wire features, RPs, etc. It just turns into a real mess. I might be well served to update from ABQ22 though I couldn't say if they've worked on the connector tools or not. I look forward to your input and thanks very much! Regards.

 

[rph5g]

Can you share the .inp or .cae file with the model in which there’s this undesirable behavior without constraints applied to the middle node ?

Hi. I was able to upload an input deck. I realize now that I did so without posting it as a reply to your note. Sorry about that and thanks again.