Partition a volume mesh (bone)

[gpapantonakis]

Hello all,
I want to simulate a three point bending test in Abaqus for a mouse bone. I use Mimics and 3-matic for modelling and volume mesh and then I import the file to abaqus for the FEA. My question is how can I create 2 partitions that divide the bone in two parts before importing it to Abaqus. The reason that I want to do that is because I want to constraint exactly the cross-section in the middle of the bone to move to the loading direction. I have tried it by selecting manually a ring of elements and then apply to them the boundary conditions but this will not give reliable results since I want to perform the 3pbt in different bones and then compare. I couldn't select the same ring of elements manually of course.

Any ideas??

Thank you

 

[gpapantonakis]

Please, could anyone recommend a possible solution?

 

[Mustaine3]

Partitioning is a geometry operation. It cannot be done on a mesh.
You have to bring the geometry to /CAE, partition that and then mesh it in /CAE.

 

[corus]

If you're applying a 3pt bending test then you wouldn't be applying the load or restraints to a cross section, but as the name suggests, to a point. Just select a node to apply the load to, or, better still, use contact with a rigid body which has the load applied to. It'll take longer to run with contact but then you're likely to apply the load over a region rather than a single point, which would give you very high stresses at that point.

 

[IceBreakerSours]

There are many ways to do this but, before I make any suggestions, I would like to see a schematic/cartoon/picture of your experimental set-up.

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[gpapantonakis]

First of all, thank you for your replies.
I attach 2 pictures of my setup. The boundary conditions I have already set are:
1) The supporting beams cannot move in any direction
2) The loading beam can move only in y direction for 1 mm. (It's a mouse bone with diameter ~2mm). So I apply a displacement and not a load in my set-up and I measure the reaction force to create the Force-displacement curve that I need for my experiment
3) There is a ring of element under the loading beam that is constrained to move only in the y-direction. These elements are chosen manually with a drag-box.

The concept of my general question is:
I'll test mice bones of different ages and I want to avoid limitations coming from boundary conditions that are not defined the same way. If I choose ring of elements in 24 different samples that I have, they will never be selected correctly in the middle of the bone, or exactly under the loading beam or the same number of elements or or or...

 

[rstupplebeen]

I believe that #3 could be removed from the analysis if friction were included. You may need to provide global stabilization until contact occurs to remove any rigid body motions. This will avoid the arbitrary selection of noes to be constrained. This will allow the bone to settle in the test fixture.

I hope this helps.
Rob

Rob Stupplebeen
Rob's Engineering Blog
Rob's LinkedIn Profile

 

[IceBreakerSours]

Why is #3 is required? This is just a regular 3-pt bending test, isn't it?

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