[CIG-SHORT] Pylith Drucker-Prager Plasticity Problem

[Brad Aagaard]

Jianbo,

Use the allow_tensile_yield properties for the Drucker Prager material. 
For example, with the 3-D Drucker-Prager material,

[pylithapp.timedependent.materials]
elastic = pylith.materials.DruckerPrager3D
elastic.allow_tensile_yield = True

See the PyLith discussion of the Drucker Prager materials in the PyLith 
user manual for more information.

Brad

On 10/4/12 6:03 PM, Jianbo Zhu wrote:
> To whom it may concern,
>
> I am a postdoc at Caltech with Professors Ares Rosakis and Nadia Lapusta. I am using Pylith to compute the plasticity during fault rupture. But I met a problem after running Pylith.
>
> The example is a very simple 2D horizontal fault rupture. The material properties are density 2700, vs 3000, vp 5291.5, friction angle 20 degree, cohesion 1 MPa, dilatation angle 1 degree, which are the same as those in Pylith "tests" files. After running pylith by command "pylith tri3.cfg tri3_100m_gradient.cfg", an error occurred as:
>
> "RuntimeError: Infeasible stress state - cannot project back to yield surface.
>    alphaYield:       0.148583
>    alphaFlow:        0.00675674
>    beta:             3.67479e-05
>    trialMeanStress:  0
>    stressInvar2:     0
>    yieldFunction:    -3.67479e-05
>    feasibleFunction: -3.67479e-05"
>
> I need the computation results urgently. Would you please tell me the reason for this error and how to solve it? Thank a lot!
>
> Attached is the zip file for my example.
>
> Best regards!
>
> Yours sincerely,
>
> Jianbo Zhu
>
>
>
>
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>
>
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