Insertion/ retention forces

FOL

Hello everyone,

I’m trying to estimate the required force to clip and unclip a plastic part into a metallic panel. The expected outputs are a correct behavior of the clips and the required force dependent on time or displacement.

In the model, I fixed the metallic panel and applied a displacement in the plastic part. In addition to this, I applied frictionless contacts on the faces that are contacting with the panel.

After simulating it in Mecway, I have two main challenges:

1) The simulated behavior of the clips is not the expected one. The clips are deformed on the beginning but are not entering in the hole.
2) I don’t know how to plot the reaction force on the metallic plate for each step of the simulation.

Thanks for your advise.

Fol

Victor

Hello Fol

Mecway doesn't support open/close type contact between two parts yet so unfortunately this won't work. The frictionless support is for sliding of one part against a rigid surface. If you can consider the metal part to be rigid, then you could use frictionless support on the plastic part and not have any mesh for the metal part.

You can also export it to .inp format and solve with CalculiX which does have contact and friction. You would need to add the code for contact by hand though. This is something that'll be easier to do in the upcoming version 4.

Sergio

Is a little complex problem, you have big deformations, contact and surely material plasticity. Have made in the past some test of a plastic ring being pushed in an outer can and results were not related with push in/out measured forces, simulation results are very influenced by mesh size and friction coeficcient. I remember that when I plot the load/deflection curve, for every line of nodes in the plastic ring there was a peak in the curve... so to smooth the curve I need to use a very small mesh, then for solving contact and nonlineal with a very fine mesh... hours to make a run!

For having an idea if the clip will work (not break during clipping) you could do a no lineal analisys, just pushing the outside diameters of the "wings" of the clip to the metal diameter. Avoid contact for the first analysis, and use half or quarter model if is simmetric.