Goodmorning everyone, I was playing around with “compression only” constraint and I saw something weird in the results. The model is very simple: a cube with a compressive force (surface traction) on the upper face, whilist on the opposite compression only constraint is activated.
I would expect a simmetrical expansion of cube lateral faces when compressed, instead as can be seen from the results, something is wrong, there’s a slight asimmetry in deformation… am I missing something? Thank you in advance for your help!
I don’t understand why, since load and contraints are already symmetric: it is like some kind of rigid body motion is present, but in such a case it would be a numerical error I guess…
Compression-only constraint uses GAPUNI elements which are basically simple contact elements. So this constraint is like frictionless contact with rigid surface. And thus you need additional boundary conditions to prevent lateral motion.
