Errors in 3 Point Bending test on Clavicle - Support Beam invades Bone 2

[magrimmelprez]

Hi! (I'm new here, sorry if I make dumb questions)

So, I am simulating a three point bending test on a human clavicle for one of my researches.
I was able to simulate a three point bending test for a different bone (mice femur) with the same boundary conditions and other properties, but for the clavicle, I get very odd results that I haven't been able to fix yet.

As you might see in the picture that I tried to attach, when I apply a 1mm displacement through a Loading Beam, my bone deforms, but it goes through the Support Beams and allows the Loading Beam to invade it as well.
Right now I am working with the following conditions:

My bone is meshed with C3D10, around 40000 elements.
I have an interaction property between bone and beams that is Mechanical -> Tangential Behavior and Mechanical -> Normal Behavior.
Besides, my Boundary Conditions are:
Support beams are ENCASTRE
Loading Beam can only move in y direction and has a 1mm displacement in the -y direction.
Bone: The Reference Point of my bone (a point I created in the middle) can move only in the y direction.
Furthermore, I have a Coupling Constraint for some nodes around this reference point (in the same plane) in all directions.

Should I change any of these to obtain a better solution?
As I said, I ran these same properties on a femur and I got good results. (No beams in my bone )

I hope I provided info enough!
Thanks in advance!

Marie

 

[testing]

You probably want to revisit your constraints to verify them. You could add contact definitions, but that's likely overkill and will increase your simulation time. Keep in mind that the displayed results are exaggerated, your bottom results aren't as different as you think: top graph has deformation scale factor of 17.17, while the bottom has a deformation scale factor of 1.76. It's tough to tell exactly, but it looks like your support beam deflections are pretty similar in both cases, they just look incorrect due to the scale factor. You can change the scale factor in the "Options->Common" dialog box.

 

[Mustaine3]

- set deformation scale factor to 1
- check direction of contact face on rigids

If you still see penetrations, then I assume the penalty stiffness is too low, because of low material stiffness. Scale penalty stiffness up or switch to direct method (=Lagrange multipliers).

 

[magrimmelprez]

Thanks!
I'll try what both of you said!
But the deformation scale helped a lot already!
Now I feel dumb haha