Linear and Powerlaw strain hardening question?

[naveeniisc]

Hi Moose Experts,

I'm new to the MOOSE environment and trying to run some Tensor Mechanics examples. I need to verify analytical solution of this paper "Plastic Relaxation of the Transformation Strain Energy of a Misfitting Spherical Precipitate: Linear and Power-Law Strain Hardening" with moose numerical solution. Can anyone suggest me where should I start? Is this sufficient to start with this examples projects/moose/modules/tensor_mechanics/test/tests/recompute_radial_return/isotropic_plasticity_finite_strain.i and projects/moose/modules/combined/test/tests/power_law_hardening/PowrLawHardening.i ? Paper Attached in this discussion.
Earmme1981_Article_PlasticRelaxationOfTheTransfor.pdf

Thanks for the assistance!
Naveen

[crswong888]

@hrishiv @albiedahal

[jiangwen84]

If you are new to MOOSE, I suggest you start to read the Tensor Mechanics documentation, i.e. https://mooseframework.inl.gov/source/materials/IsotropicPowerLawHardeningStressUpdate.html

[naveeniisc]

Thank you jiangwen84 let me go through this.

[naveeniisc]

Hi Moose Experts,

I could create the input file for the problem as mentioned in the last post (for isotropic plasticity

), however the solution is not converging.

I have read this information here :https://mooseframework.inl.gov/modules/tensor_mechanics/Convergence.html

, but could not understand the process of setting up the convergence criteria?

Can someone please explain the convergence criteria in detail.

Thanks in advanced,
Naveen

JKlee_test.txt

[naveeniisc]

Hi @jiangwen84 @

can you explain my above post in detail?

Thanks in advance
naveen

[jiangwen84]

For mechanics problem, you have to use Global Strain system to setup strain periodicity. https://mooseframework.inl.gov/source/actions/GlobalStrainAction.html

Could you start with a simpler problem? e.g. 2D, without periodicity. Once successfully, add periodicity, and then 3D.

[naveeniisc]

sorry about late reply thank you @jiangwen84. i will follow your instruction.

[ngrilli]

Dear @naveeniisc

I noticed you fixed the displacement only on one node, called boundary = 100

Can you try more standard boundary conditions for mechanics problems,
like constraining your cubic RVE in a corner,
something like:

[./z0_bot]
type = DirichletBC
variable = disp_z
boundary = back
value = 0.0
[../]

[./y0_bot]
type = DirichletBC
variable = disp_y
boundary = bottom
value = 0.0
[../]

[./x0_bot]
type = DirichletBC
variable = disp_x
boundary = left
value = 0.0
[../]

Convergence problems are likely to appear if you don't constrain properly your system.
Best Regards,
Nicolò Grilli
National University of Singapore

[naveeniisc]

Dear @ngrilli thanks for suggestion, let me try your solution.