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ABAQUS embedded regions
Hello,
I am trying to find out if someone has information about the "embedded region" constraint in Abaqus. I am trying to model a very simple short fiber in a matrix (short cylinder inside a block). The model is purely elastic. The problem is, no matter how high I assign the values of the E modulus of fiber, I always get equivalent properties of composite (fiber + matrix) equal to matrix properties.
I can then assume that with embedded region there isn't really any contact defined between matrix and fiber that's why I get very low equivalent stresses and stiffnesses.
Does anybody have an idea what's wrong there? Is the embedded region algorithm flawed? My colleague does a model with 1000 carbon nanotubes embedded in a matrix and still gets matrix properties as a result.
Is there something we are missing (i.e. embedded regions is not enough constraint) or is embedded region algorithm flawed?
P.S. I couldn't also find much documentation about how embedded region works.
Thanks!
will depend upon fiber volume fraction
Hello Yasmine,
To have a remarkable change in equivalent stiffness, I think, you should also have a significant fiber volume fraction. As it is basically the rule of mixture that will govern the behaviour of the longitudinal elastic modulus.
Otherwise I didn't find any discepancy in the embeddement technique which worked quite well for me. I used this to model reinforced bars within a concrete beam.
regards
asim
Hello Asim, I
Hello Asim,
I understand what you mean. My volume fraction is quite large.
I just did the same model but with tie constraints instead of embedded regions.
The thing I found is that if the fiber (cylinder) is completely inside the matrix, and I apply boundary conditions at the matrix surface, I get low properties which means somehow the fiber is not loaded.
I tried to do embedded regions constraint with a long fiber (cylinder going completely through the matrix) and it worked! I got correct properties compared to rule of mixtures.
I am not sure what I am doing wrong!
Hello Yasmine, I think I
Hello Yasmine,
I think I am confused about the model description. You said that you did the model but with tie constraints instead of making embedded. Does it mean that you modeled an extruded hole in the matrix and placed the cylindrical fiber there and applied a tied constraint. In that case your embeddment is bound to fail since the fiber will not be inside the host region. It would be better if you can attach a figure of the model depicting the tie to make things clearer.
regards
asim