Accessing time-evolving material density in Solid Mechanics

[vabufano]

Hello everyone,
I'm working on an analysis where I need to reduce the material density over time in a specific subdomain #31898
I'm currently focused on the evaluation of the evolving density value at every time step of the simulation.
I've implemented the density reduction logic, but I'm having trouble exposing the density value as an accessible variable/property at each time step. I've been looking for an AuxKernel to do this, but with little success (taking some inspiration from what can be done in PorousFlow with PorousFlowPropertyAux).
Does anyone have experience in implementing a custom AuxKernel or an alternative approach to track and access an evolving material property (like density) within the Solid Mechanics module?
Any suggestions would be greatly appreciated.
Thank you in advance for your support!

[GiudGiud]

Hello

Do you have a material where the value is controllable?
The control system is intended to modify the parameter dynamically
This one for example for a Real valued parameter
https://mooseframework.inl.gov/source/controls/RealFunctionControl.html

[vabufano]

Hi!
As I mentioned in the linked discussion, what I would like to do is simulate an excavation by reducing the density and stiffness of a soil block over time.
Taking density as an example, I am currently defining it with a GenericFunctionMaterial object and using a function as prop_values that goes from the soil's initial density value down to 0 (or a very small value) from the beginning to the end of my numerical analysis.
What I simply want is to evaluate the density value within the problem domains at each timestep, so that I can be certain that: 1) the density is actually being reduced 2) the reduction is following the law I defined in the ParsedFunction I assigned as prop_values.
Please forgive me if I misinterpreted your question.

[GiudGiud]

You can output function values to an auxiliary variable using the FunctionAux

You can output material property values to an auxiliary variable using the MaterialRealAux

[vabufano]

Thanks a lot! It's working.
What if I would like also to evaluate in a similar way the evolution of the Young modulus?
I'm currently defining it with ComputeIsotropicElasticityTensor making it decreasing according to a ParsedFunction that I'm giving with elasticity_tensor_prefactor.

[GiudGiud]

The pre factor is likely not a material property but y' the Young modulus should be

Use Debug/show_material_props to see the names of the material properties

[vabufano]

I tried using [Debug] but I don't seem to have found the Young's modulus among the material properties.
To verify the reduction, I used RankFourAux, selecting the elasticity tensor as the rank_four_tensor and evaluating over time the first component which, in the case of linear isotropic elasticity, depends on the Young's modulus and the Poisson's coefficient.
Thank you!