I am trying to simulate the deformation of a plastic part when applying a force on it.
My goal is to check the pressure homogeneity on a custom made pick-up tool. I have the 3D design, I can setup the load on the surface, but I cannot define the real constraint.
If I lock the pressed surface , what I see is a 0 deformation of the surface and a homogeneous pressure applied, but the stress on the edges of the part, linked to the fact that the edges want to deform but cannot because of the constraint I have setup.
If I setup only a small part of the surface as a constraint, the entire part is deforming in the force direction.
What I need is a way to set up, or simulate, a planar constraint that allows the part to go only in the negative direction of the plane and not in the positive direction.
Do you have any suggestion about this simulation and how it could work?
Thank you very much!
What you require is a contact model. Here are my ideas on how to do it.
Contacts work better without the edge singularities so I added small rounds that are included as contact surfaces.
The following adds stability to the model, taking advantage of the symmetry to constrain the model from undesired motion. I could have actually used one of the quarters, with symmetry constraints, but the results don't look as pretty seeing only a quarter of the part.
The model was split on symmetry planes using volume regions (extruded)
The planes were constrained in their normal direction (note my Coordinate system X,Y,Z is different than yours)
Three different models can be tested, no friction(frictionless), Infinite friction, and Finite friction.
The finite friction option requires running large displacement analysis.
Here are the contact pressures.
Always be careful when evaluating stress at boundaries such as forces or constraints as modeling accurately is difficult. Once you are far enough away stresses are correct. See https://en.wikipedia.org/wiki/Saint-Venant%27s_Principle