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Re: Monitoring of tangential stress ?


Jerome Duriez a écrit :
Hello everybody.
Short question : Considering a box containing my numerical sample I'ld want to monitor the tangential stress acting on one plate of the box and I wonder if someone has already made it ?

Less short question : In fact I want even monitor this tangential stress ("tau") depending on the normal one ("sigma") : so that the ratio dtau/dsigma remains constant (to a given value) during the simulation, whereas an other control parameter would be, for example, something like a strain rate. Would you have something to say about it ??

Hi Jerome,

I did something like that but I am not sure to be able to help you.

It was with SDEC, I was able for instance to control the ratio between the stress deviator q=sigma_1 - sigma_3 and the volumetric strain epsilon_v. You can find the details in my thesis.

I think that all the elements are already, more or less, written in Yade to be able to do such a control. Indeed, with the "TriaxialStressController" engine you can impose a given normal stress component to be equal to a given value. In your case, this value is not a constant but is proportionnal to a tangential stress for instance (or reciproquely).

The tricky point when you define such simulation is the following: depending on the mechanical response of the granular assembly and depending on the value of the ratio of the two stress or strain components you want to monitor, the numerical loop used to control the stress on a wall can become instable. To limit this effect I introduced a kind of damping parameter (such as the damping wall parameter defined in the triaxialcompressionengine), but I don't think it is a clean solution in this case because you don't really know what is the influence of a such damping parameter on the simulated response...

  Good luck



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Luc Sibille

Université de Nantes - Laboratoire GeM UMR CNRS

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