Discussion Forum

Hi,

I'm attempting to model properties of a textile based on yarn level information, but am struggling to get my solver to converge. I'm attempting to create a simple setup with a mesh from TexGen (the import seems to work fine), and some simple physics examples (currently just compression).

The mesh is a simple 2x2 plain weave where I've tried applying symmetry, periodic condition and fixed constraint at the ends of the yarns. For compressive forces, my application would be two other textile layers, but at this point I'm attempting to simplify it. For this, I tested uniform pressure, and two compressing plates with boundary load, body load and predescribed displacement. My study is for stationary condition as I want to find the relationship of compression in the textile to the applied force. For materials, I've tested some wool parameters for compression, but did most of my tests with structural steel as I would expect this to yield at least something.

I would suspect that the issue is in the contact pairs due to the four separate yarns being disconnected meshes. However, I'm not sure if there is any other ways to set up th contact pairs. I could use a filled domain (e.g. air), but I'm not sure if this is a good approach for a mechanics problem like this.

I've also tried to set up some 2d simulations of the problem as well, but (likely due to the contact) they also fail to converge.

Any help would be greatly appreciated. I've attached some relevant screen captures here of my latest setup with the two plates, and the error/warning I get below. The error is generally the same for all my attempts, but warning is not.

Warning: New constraint force nodes detected: These are not stored. This only affects the reacf() operator in postprocessing.

Error: Failed to find a solution. Maximum number of dogleg iterations reached. There was an error message from the linear solver. The relative error (0.13) is greater than the relative tolerance. There was a warning message from the linear solver. Iterative refinement triggered. Returned solution is not converged. Not all parameter steps returned.