Linear constraints to couple dofs

Hi everyone,

Is there a documented example/test somewhere to demomonstrate coupling of degrees of freedom via linear (multi-point) constraints (similar to: abaqus-docs.mit.edu/2017/English/SIMACAE...ptopicmultipoint.htm )

I know that Netgen exports the .mpc file to Abaqus, and was wondering if it was possible to do the complete analysis in NGSolve itself.

Thanks,
Bhavesh

Hi Bhavesh,

we have several possibilities for various applications:

1.
Constraints over identified boundaries, typically periodic boundaries with matching meshes.
We have Periodic spaces having same values at the left and right boundariy. If you use that constraint space for a Lagrange parameter, you can impose quiet general constraint equations (see attachment).

2.
We are working currently on coupling between non-matching (surface)meshing, notebooks coming soon. This allows also coupling of different models, e.g. full 3D / simplified 2D.

3.
Mean value constraints (e.g. for modeling joints in multi-body simulations) are possible by scalar Lagrange parameters (in NumberSpace)

Best,
Joachim

Hi Joachim,

Thanks so much for the comprehensive reply and the notebook. In fact, point # 1. is what I was looking for to start with. Eagerly looking forward to the tutorials in 2. and experimenting with 3.

Let me try with the approach in 1. to see how it goes.

Thanks again,
Bhavesh