Different properties of outer elements 1

[Timusop]

I have some complex bone geometry in Abaqus, is there any way of defining the elements associated with the outer surface to have one set of material properties and the rest of the internal elements to have another set of material properties.

Another way of doing this maybe to have the first 1mm of material below the surface to have one set of material properties and the rest of the internal material to have another material property.

I would really appreciate some advice on this.

Thanks

 

[MechIrl]

Yes, you can just create an element set for the outer elements and give them a different section assignment to the inner ones.

The hardest part is usually selecting the outer elements. Depending on the complexity and size of your geometry you could try this manually using tools like 'select by angle' and display groups in CAE.

If you are comfortable with Python its easy enough to cycle through element faces and determine whether or not they're 'outer' faces.

 

[Timusop]

Thanks MechIrl,

Your suggestion has got me thinking some more...

Could I define the outer elements to be a certain depth? This might be a more difficult if the elements not hex or if there are some tricky radius bends.

I may have to model the two sections seperately and then tie them together (one inside the other).

Would the python script be a complicated one to put together?

Thanks.

 

[MechIrl]

If you can easily split the two sections then a tie constraint would be the most striaght-forward approach for this.

The python scripting wouldn't be overly complex if all you want to do is identify outer elements. You just have to cycle through all elements in the part and using the element connectivity object add any elements not completely surrounded by other elements to a set.

Things get a bit trickier if you want to add elements a certain distance from the surface to a set but again it is entirely possible using a python script. You can even do fancy things like assign material property gradients etc.