Modeling a 6 strut tensegrity

[karley]

Hi all,
I am trying to model a 6 struts and 24 cables tensegrity structure. Actually, when I assign "no compression" to my cables, it gives me a "Too many attempts made for this increment" error.
Does anybody know how can I fix this problem?

 

[IceBreakerSours]

"Too many attempts made for this increment" error

That error message can be due to various issues. Without knowing more about the model, it will be hard to provide any help. For example, what kind of analysis are you performing (static/dynamic..)? , what type of elements are you using (trusses, beam, frames, ..)?, what type of loading is being applied, what are the bc's?

http://www.eng-tips.com/faqs.cfm?fid=376

 

[karley]

Thank you for your response. I am trying to perform static analysis and the beam element was chosen for this. I applied concentrated force on three nodes and I fixed the opposite three nodes(U1=0,U2=0,U3=0).
I think that the problem is that I did not define prestress for the cables which results in singularity in the K matrix. Do you know how can I define prestress in ABAQUS for a material?

 

[IceBreakerSours]

Numerical singularities are due to rigid body motions. Nodes on structural elements like a beam have six degrees of freedom and you have fixed only 3. Pre-stress has nothing to do with this issue.

http://www.eng-tips.com/faqs.cfm?fid=376

 

[karley]

I just fix the other 3 DOFs, but I have the same error. the point is that the structure is unstable cause the prestress is necessary to make it stable. could you tell me how can I define prestress on cables? I appreciate your kind help.

 

[IceBreakerSours]

Numerical singularity has nothing to do with pre-stress.

Nevertheless, search initial conditions, type=stress in the documentation.

http://www.eng-tips.com/faqs.cfm?fid=376