I am trying to model fluid flow through a porous material. I have modeled the solid matrix in umat as a type of hyper elastic material, and would like to use the soils consolidation to do the analysis, however, even though according to the following thread it seems doable, it seems like the solver does not communicate with my umat when I use *Soils.
I have examined a couple of test cases:
-I tested the input file using Abaqus built-in elastic material for the solid matrix, solving with *Soils, and it works fine and I get what I expected.
-I have checked the umat using the same input file only with a simple static step, and replacing the elastic solid matrix with the user defined material. That works fine too.
I put in some write statements and output the deformation gradient, elastic stress and strain values, and the stresses are zero everywhere, and strain values are wrong (I have prescribed the displacement, thus strain is known). The strain does not seem to be the actual strain because 1) the deformation gradient and Cauchy-Green tensors remain identity all throughout, 2) stresses remain zero.
This makes me wonder if it is impossible after all to use a user-defined material in the soils analysis, even though it does not make much sense. I could not find anything in the documentation regarding this. In the *Soils documentation it looks like you can only define the material properties using *elastic, *bulk modulus, etc. which would imply that umat can not be used? Not sure if lack of that information means this is not feasible.
Please let me know if you have any experience with this.