Recently I learned the use of pylith and now need to simulate the distribution of stress within the lithosphere under gravity. I defined the boundary conditions and initial stress, and simulated the time for 20000 years, but the results showed that the Cauchy stress did not change much between the initial step and the final step.

What I wanted to determine was whether pylith could be used to calculate deviatoric stresses, which play a very important role in lithospheric deformation.

Thanks！ My previous simulation was using pylith2.2.2.
I read the example in pylith3.0.3, can I simulate the deviator stress by following the steps below:

Turn on gravity

Given reference stress state

Set the material to viscoelastic (because I need to simulate the deformation on the time scale of tens of thousands of years, it is not appropriate to consider the crust as elastic)