100+ warnings for a failed Nonlinear Static Stress Simulation (Help please!)

[Staerlinc]

Hi everyone!

I'm just trying how an orgami structure, such as Miura, behaves in realistic simulation. When I tried to fold the component to an ideal folding state (shown in picture) by applying some nonlinear forces, it always failed with hundreds of warnings came out (detail is attached).

I used rubber as "creases" of origami and panels are made of stiffer substance such as plastic, and components are all bonded. One of the panels is fixed as shown in the picture.

I tried to apply multiple forces in circles shown in the picture and failed. Then I reduced the force to only one (shown in picture) but failed as well, and the details seem to be the same. Could someone please enlighten me where I was wrong and give me some hints about how to correct it?

[henderh]

Hi @Staerlinc,

I'm not sure why the solution isn't converging, would it be possible to share the design, to take a closer look?
File -> export and attach it here, or File -> Share the web link

I'm curious if a prescribed displacement might succeed, in place of the forces.

Best regards,

[Staerlinc]

Hi Henderson,

Thanks for the reply! Attached is the file. 

In fact, I'm interested in studying the mechanical performance as well as its folding process of the orgami while applying some force on it. I've done a series of modeling of origami units in Design Section (and such geometric simulation works well in small magnitude units).

I'm very new to the Simulation Section and not sure if "prescribed displacement" is what I need. Anyhow, thanks for your attention!

Best Regards,

[henderh]

Hi @Staerlinc,

I believe the reason the solve fails is that the stiffness of the rubber connector is extremely low (0.003 GPa) which makes it like an under-constrained 'hinge problem'. The solve can succeed by using a stiffer material, and lowering the load, but the deformations won't be hinge-like:


Although the rubber material is specified as a study material in a nonlinear study, due to the way it has been defined, only the linear properties will be used. The materials in the nonlinear material library have nonlinear properties, but unfortunately rubber isn't included. We do support hyperelastic materials, but it must be created as a new material, using constants or curve data:


I hope this helps!
Please let us know if you have additional questions, or comments.

[Staerlinc]

Hi Henderson!

Sorry for the late reply and thanks for your analysis.

So do you mean that defining a new material to be applied as "hinge" with my own data can be a solution? And it would be so kind of you if you could show me where can I start first (I mean the button with which I can enter the 'definition section').

Thanks very much!