[aspect-devel] Strain weaking - continental extension model

[John Naliboff]

Hi all,

Apologies, I did not release I had only responded to Phil when I replied to his email! The message and files I sent are located below.

Cheers,
John

*************************************************
John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis

Hi Phil,

That's odd you are getting a density inversion. I've attached a modified version of the continental extension cookbook with strain weakening, which uses the strain invariant (e.g., not full strain tensor) to track strain. 

The option to use the full strain tensor exists, but there is no need to use it unless you want to track finite strain through time. In that case, the best option is probably to track the finite strain tensor with particles and use a compositional field for finite strain.

There is an option to output the modified friction and cohesion angles, with examples located in the tests folder.

Please let me know if you have any questions about the attached parameter file, additional options or if any errors pop up with the parameter file.

Cheers,
John





> On Sep 19, 2017, at 1:39 AM, HERON, PHILIP J. <philip.j.heron at durham.ac.uk> wrote:
> 
> Hi Anne, 
> 
> Thanks for the email! These are great - thank you. John Naliboff emailed me a while back - looking back over the email it looks like we had an exchange between ourselves and not the group! Thanks for the help!
> 
> It worked out well - no density inversion. I was implementing the strain weakening incorrectly. 
> 
> Thanks! 
> 
> Phil
> From: Aspect-devel <aspect-devel-bounces at geodynamics.org> on behalf of Glerum, A.C. (Anne) <A.C.Glerum at uu.nl>
> Sent: 19 September 2017 09:29:52
> To: aspect-devel at geodynamics.org
> Subject: Re: [aspect-devel] Strain weaking - continental extension model
>  
> Hi Phil,
> 
> Hope this answer is not too late for your talk, but there are some tests using the strain weakening functionality of the visco plastic material model:
> visco_plastic_complex.prm
> visco_plastic_yield_strain_weakening.prm    
> visco_plastic_yield_strain_weakening_full_strain_tensor.prm
> Perhaps they’re helpful? I’ve been running some extension models with strain weakening, so I’m curious to hear whether you still get your density problem.
> 
> Cheers,
> Anne
> 
> 
>> On 11 Sep 2017, at 12:26, HERON, PHILIP J. <philip.j.heron at durham.ac.uk <mailto:philip.j.heron at durham.ac.uk>> wrote:
>> 
>> Hello there, 
>> 
>> I've been asked to give an informal chat to some structural geologists on ASPECT usability this week, so I'm just building up some simple models. 
>> 
>> I've been playing around with the continental extension model and am looking to add on strain weakening to the cookbook example. However, each time I've tried to implement it I get a strange density inversion in the model. 
>> 
>> Does anyone have an example of how to implement simple strain weakening, say for this cookbook example? There are no examples kicking around that I can see. 
>> 
>> 
>> 
>> Thanks in advance for the help!
>> 
>> Best, 
>> 
>> Phil
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> 
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