Tricking ABAQUS in defining materials

[mhajinaw]

I am wondering whether it would be possible to "trick" ABAQUS in order to assign two different material properties on the same element. From what I've tried so far, if I assigned two different section assignments with two different material properties on the same part, ABAQUS will only consider the second section assignment. The first one will not be used.

The reason why I'm trying to do that is I want to model an element which consist of something like an isotropic matrix and anisotropic fiber. Does anyone have any suggestion?

 

[IceBreakerSours]

Why not simply use an anisotropic material law?

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[akabarten]

Hi,

There is no option to assign two different materials to one element.
But you can duplicate element to share the same nodes and assign different materials to each element.

Regards,
Bartosz

VIM filetype plugin for Abaqus

https://github.com/gradzikb/vim-abaqus

 

[Mustaine3]

Maybe this useful:
Abaqus Analysis User's Guide 35.4.1 Embedded elements

 

[IceBreakerSours]

As I said, it is 'straightforward' to choose an anisotropic hyperelastic material such as Fung or Holzapfel-Gasser-Ogden. HGO is stretch-dependent anisotropic, whereas the other options are not.

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[mhajinaw]

Thanks for all the suggestions. I'll look into the details.

The available HGO model indeed has taken into consideration the matrix and fiber. However, I want to go another step. What I'm intended to do is to model fracture. I want to assign different failure criterion for the fiber component and the matrix component. This is where I think the available HGO model is not suitable. As far as I understand, Abaqus only consider the material as a single "bulk" material.

If anyone has different ideas to model this kind of problem, feel free to share.

 

[IceBreakerSours]

Why do you want to model fracture? What's the ultimate goal? Do you have access to experimental data for input and validation? What's the plan? Given the content of your posts, I fear the goals may not align with reality.

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[mhajinaw]

Probably I should provide a brief information about the simulation that I'm planning to do. I want to model the fracture on soft biological tissues. I want to see the effect of the micro-sturcture on the pathway of crack or delamination. You'll probably know better than me that biological tissues have different micro-structure such as collagen and so on. To simplify the problem, I'll consider only the matrix and the collagen fiber just like composite structure. If I can assign different failure criterion for these two components, I'll probably see how the crack propagation/delamination differ if let's say the collagen reach the failure criterion first or vice versa.

So far, by duplicating the elements as suggested Bartosz, I'm able to assign the material properties. Now, I need to work on whether it will work in the case of failure. If you have other ideas on tackling this problem, we can always discuss it

 

[IceBreakerSours]

Thank you for that information. It is good to brainstorm before executing - always a good thing.

However, after brainstorming, one has to have a strategy. None of what you wrote makes me feel like you have the elements of a sound strategy and the skill set to follow through with a strategy. Are you a fracture mechanics expert? Are you a composites expert? I doubt it (because, chances are, if you were, you wouldn't be asking these kinds of questions).

So, what experimental data do you have or can gain access to so you can validate your model? What input parameters do you need to feed in to the model? If you do not know the answer to such questions, then you need a LOT of supervision for a year or two! Going by prior experience on these forums, you probably do not have excellent supervision either. So, in my experience, odds are heavily against you accomplishing those goals. I suggest you speak with your supervisor and colleagues before you commit to any plan of action.

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