Enforced displacement, roller boundary, and then a periodic boundary conditions

General Discussion
1

Hello FF++ developers and users

I’d like to calculate the deformations of a square composite structure subjected to uniaxial tension at an angle of 45°.
Assuming that the square composite structure is symmetrical vertically and horizontally, the analysis should be possible with ① in the diagram above.
So what about uniaxial tension in the 45° oblique direction (②)?

250217_FF++_COMMUNITY
250217_FF++_COMMUNITY2167×1106 262 KB

First, the program was developed assuming that the quadrangle is subjected to uniaxial tension so that the strain is uniform in the 45° diagonal direction.
It is assumed here that the nodal displacements can move arbitrarily on the four-sided boundary after deformation.
How can this code be improved to perform the analysis described above?
250217_FF++_COMMUNITY.edp (8.3 KB)

I think the boundary condition would be a combination of enforced displacement, roller boundary, and then a periodic boundary conditions, is there any way to do that?