Contact between touching faces

[NewJoker]

Hi,

I just realized that multiple mesh analysis is not supported in FreeCAD and parts have to be fused using boolean union or boolean fragments tool. But if their neighboring faces are not separated by some distance then meshing will result in continuous mesh and there's no need to apply tie constraint and contact anymore (besides, in most cases it wouldn't be possible to select the right faces for contact since individual parts can't be hidden after they are fused with boolean tool). So basically, contact and tie constraints can be applied only to parts separated by some distance, right ? However, in FEA we generally try to avoid gaps between surfaces in contact because they might cause convergence issues due to initial rigid body motions.

So for example, if I want to analyze a typical Hertz contact problem, I have to offset the two parts by some distance to apply contact and to avoid the parts being meshed continuously ?

That's a serious limitation. Would it be difficult to remove it (I don't know the reason behind it) ?

[bernd]

you are correct! ATM there has to be a gap.

_UR might know more,
he is FreeCAD FEM contact "hero" ...

[Laurie Hartley]

So for example, if I want to analyze a typical Hertz contact problem, I have to offset the two parts by some distance to apply contact and to avoid the parts being meshed continuously ?

tschrader posted this link - it is a video about creating hinges across gaps. I have had a look at this and will be trying it out on a model I am making (anything could happen!). Anyway it may be related to your question.

https://forum.freecadweb.org/viewtopic. ... 95#p532495