Calculate/Measure Crack Length

[rh201]

Dear all,

In the phase-field fracture simulation, how to calculate and output the crack length to a .csv file? Or how to do it in the post-processing? Thanks.

[GiudGiud]

Are you using XFEM too?
How is the crack being simulated?

[GiudGiud]

is there a boundary or block along the crack?

[rh201]

The boundaries can be set for a simple expecting cracking path, but what if arbitrary crack propagation?

[GiudGiud]

if you dont have a boundary or a block, then most of the postprocessors / VPPs wont help you

One thing you can do is :

• use an auxkernel to create an auxvariable field that measures the distance to the crack
• use a mesh division on create regions based on the bins of that auxvariable
  https://mooseframework.inl.gov/source/meshdivisions/FunctorBinnedValuesDivision.html
• then use a VPP to gather the integrals over those divisions
  https://mooseframework.inl.gov/source/vectorpostprocessors/MeshDivisionFunctorReductionVectorPostprocessor.html

note here than Functor can be an auxvariable but cannot be a regular material property
so you will neeed to also use a MaterialRealAux to convert the material property to an auxiliary variable

[lynnmunday]

Can you just divide by the crack thickness to get the length? Isn't there some kind of phase field smoothing distance you could use for the thickness?

[rh201]

Yes, there is a length-scale to diffuse the crack, thanks for the help. @lynnmunday @GiudGiud

[lyyc199586]

I built a filter of Paraview to track the phase field crack tip, it is purely postprocessing in Paraview, you can have a look https://github.com/lyyc199586/pvfilters