Hello:
I apologize for causing any inconvenience, but I am really new to to Abaqus and especially, using it with user subroutines!
I have a project where I am trying to update a (sort of) damage parameter via usdfld, but I also need the umat to redefine my stiffness matrix for my model. I believe the getvrm utility routine cannot be used in umat, but can be used in usdfld (that is my main reason for using usdfld!).
Attached in this question is a .inp file that is the abaqus input file. I also have a user subroutine where I have sdvini, usdfld, and umat subroutines.
At this stage, all I want is for the Abaqus job to properly recognize my subroutines. That is the reason for the write commands in my fortran files. So far, the subroutines sdvini and umat are causing no problem and are running perfectly fine. It is the usdfld subroutine that is, for some weird reason, not getting recognized!
The following error message keeps popping up whenever I am trying to run this file:
"The option *User Material, Type=Mechanical completely defines the material behavior. It cannot be used with an option that defines part of material's behavior."
I thought that after the number of properties, for the user defined material, were defined, the other dependent properties could be introduced and updated via usdfld. For some reason, here it is one or the other!
Could any of you guys please look into my .inp file? I am pretty sure I am making a mistake in not including some keywords somewhere! I have inserted the following keywords:
*User Defined Field (to activate USDFLD)
*User Material, Type=Mechanical (to activate UMAT)
I am pretty sure I am missing something else! Meanwhile, I am also doing my best to look into some possible papers or examples of an inp file where perhaps both umat and usdfld are used.
Thank you very much!
Mousumi Ghosh
Hello guys:
I finally figured this out! It turns out that one cannot simply use *dependencies keyword (for USDFLD) with *user material (for UMAT). You just have to type Initial Solution, Type=Field, Variables = n
Abaqus can be quite restrictive when it wants to! But nonetheless, it is a useful FEM software!
Thank you guys!
Dear Mousumi Ghosh
could you please describe in details how to use UMAT with USDFLD. Because i have the same problem
thanks in advance
Thank you very much for showing what you figured out, Mousumi.
Regards.
Dear Mousumi Ghosh ,
I'm working on numerical simulation of bone remodeling. I'm using a mathematical model that relates Young's Modulus and density via: E=3790*Rho³.
You can see the rate of change of the density in the attached image.
Do you know how to set the module dependency on density, using the UMAT subroutine? In other words, how can I create a material property dependency on something?, for example density or temperature.
Thanks you in advance for your help.
Hi Esteban Lianos,
Did you find the answer? I am also having same problm.
Hi, Md. Tariqul Hasan
You can use as a reference the thesis Numerical simulation of bone adaptation to mechanical loading, by Jacobs C. Rae. In this work the author shows how to implement a model of bone remodeling. So, you can develop your own model from the model implemented by the author.
Regards,
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