Cable with sections of different material

[rgduarte]

Hi, once again.

i'm having trouble in modeling my bracing system, I've a design in which I've a cable with sections of different material. The problem is that the program returns the message "MAX TOOL" on the first iterations - clear sign of instability- although I've fixed every rotation and off plane displacement on the intersection nodes.
I've tried to model the bracing with elfrm on the end sections (S500) but without any success.

I'll be thankful for your help.
My simplest model (I've others where i use tensegrity proprieties, but if i can fix this one i (hopefully) can fix the more complex ones) :
https://www.dropbox.com/s/o892e1ufz3ms3 ... n.spf?dl=0


Thank you

[seismosoft]

If you try to run eigenvalue analysis with your model you will not get any results, which is a clear indication that parts of your structure are not connected well.
The internal nodes of the braces are linked to the rest of the building with truss elements. This means that the translational DOFs of these nodes are restrained, however the rotational DOFs are entirely free. This is what causes the instability problems.If, for example, you change the truss elements to elfrm elements (that would also restrain the rotational DOFs) your model should run without problems.

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[rgduarte]

Thanks for the answer.
Thus, the elfrm approach was my first try on modeling the bracing element, but even with pinned elements on both ends of the bracing element - i.e M2 and M3 release then S500 elfrm then SMA then S500 elfrm with M2/M3 release - with x+rx+ry+rz restrained nodes on the two nodes in wich the element changes from S500(elfrm) to SMA(truss) and SMA(truss) to S500(elfrm) - I get M2 and M3 (as well as V3) values on both ends on the S500 elements, wich is something that i don't expected since the bracing element should behave like a cable both on the SMA section and on the S500 section.

[seismosoft]

Have you tried using a force-based convergence criterion?

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[skhosravi]

Hi there,

I have the same problem with the same materials! I am using one bracing which has 2 different part (Steel and SMA). I modeled as truss members but I have error in my answers.
I think they should be pinned at both ends. Also they should work only in tension.
how should I model this?