Noise in the Stress-Strain curve

[YASH PANCHAL]

Dear Prisms team,

I did the simple tension simulation for one of the copper alloys using the PRISM. The microstructure is of 16x16x16 Voronoi tessellation generated using DREAM.3D.

I got the following result from the stressstrain.txt file.

As you can see, after 15% of the strain value, the noise is coming. I want to know why it is coming? And what is the significance of this noise in the stress and strain curve?

I also want to ask, how can I get to know from the simulation result when and at what per cent of strain value the sample will break? 

Thanks and regards,

Yash

[Mohammadreza Yaghoobi]

Hi,

Can you share your input files for this simulation?

Also, what model (rate-dependent, rate-independent, rate-independent2) are you using?

Regarding the sample breakage, PRISMS does not have damage or failure model right now. So it cannot predict that.

Thanks

Reza

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[YASH PANCHAL]

Dear Mohammadreza,

I have just emailed you all the files required for this simulation and I am using the rate-independent model for this simulation.

Thanks

Yash

[DANISH KHAN]

Hi,

I also dabbled with the similar problem. Try playing around with your CP Model parameters.

Regards,

Danish

[YASH PANCHAL]

Hi Danish,

Can you tell me which parameters should I change as CP Model parameters have too many input parameters?

I also found out something during some other simulation.

Up to increment: 1179 in each nonlinear iteration, the current residual getting reduced because of the linear iteration.

But after increment 1180 no linear iteration was performed for the nonlinear iteration numbers 1,2, and 3. Because of this, the current residual value was also high and not reducing after each nonlinear iteration.

This might be the reason for that noise as the error is too big and only one nonlinear iteration is performed for the rest of the increment.

Now, this noise might be eliminated if all the linear iteration performed well but which parameters should be changed in order to do the same?

Regards,

Yash

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[Mohammadreza Yaghoobi]

Yash,

Can you try the rate-dependent constitutive model with this and see if it still generates the spikes and noises.

Reza

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[YASH PANCHAL]

Now when I am using the rate-dependent model following error is coming,

New input parameters for rate-dependent model,

For phase one - 

# Flag to indicate if User Material Model is enabled
set Enable User Material Model                   = true

# Flag to indicate if User Material Model is enabled Phase 1
set Enable User Material Model 1                 = true

# Number of User Material Constants in a Material model Phase 1
set Number of User Material Constants 1          = 12

# Number of User Material State Variables in a Material model Phase 1
set Number of User Material State Variables 1    = 1

# Material Constants in a Material model Phase 1
set User Material Constants 1                    = 1e-3, 0.05, 1.0e-6, 1.0e-6, 10000, 10000, 0, 0, 0, 0, 0, 0

# Material State Variables in a Material model Phase 1
set User Material State Variables Initial Values 1        = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0

For Phase two - 

# Flag to indicate if User Material Model is enabled Phase 2
set Enable User Material Model 2                  = true

# Number of User Material Constants in a Material model Phase 2
set Number of User Material Constants 2              = 12

# Number of User Material State Variables in a Material model Phase 2
set Number of User Material State Variables 2        = 62

# Material Constants in a Material model Phase 2
set User Material Constants 2             = 1e-3, 0.05, 1.0e-6, 1.0e-6, 10000, 10000, 0, 0, 0, 0, 0, 0

# Material State Variables in a Material model Phase 2
set User Material State Variables Initial Values 2        = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0

[Mohammadreza Yaghoobi]

In the line :

set Number of User Material State Variables 1    = 1

The value is wrong. It should be equal to the number of state variables which I guess is 62. Please try this and see how it goes.

Best

Reza

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[YASH PANCHAL]

Still the same problem.

[Yash Panchal]

Dear Reza,

I did the simulation of a single-phase part with a rate-dependent model, and it is not giving any error.

I followed the same method to do for dual-phase and it is still giving the same error.

Regards,

Yash

[Mohammadreza Yaghoobi]

The mulitphase framework is working for now for rate-ndependent version. 

Let me see how can I make it running for multi-phase version.

Can you share your input files here so I can test those.

Thanks

Reza

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[Yash Panchal]

Dear Mohammadreza,

I have just emailed you all the files required for this simulation.

Thanks
Yash

[Yash Panchal]

Dear Mohammadreza,
Any update on the multiphase rate-dependent model?

Regards,

Yash

[Mohammadreza Yaghoobi]

The current rate-dependent model needs some modification for multiphase which will come with the next patch.

You can use the rate-independent for now until the next release.

Thanks

Reza

On Jan 30, 2022, at 8:57 PM, Yash Panchal <20mm...@iiitdmj.ac.in> wrote:

Dear Mohammadreza,

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[Yash Panchal]

Okay.

Can I know the tentative date of the next patch release?

Thanks,

Yash

[mohammadreza yaghoobi]

Yash,

I added a new patch for rate dependent multiphase. You can find the example here:

https://github.com/prisms-center/plasticity/tree/master/applications/crystalPlasticity/fcc/simpleCompression_RateDependent_Multiphase

Don't forget to use the calculatePlasticity.cc and userFunctions.cc of the RateDependent model when you're running this example.

Reza

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