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Re: Some questions


/1) *Is it possible to have a hertz mindlin contact law instead of a hooke's contact law between granular particles?*/
Anton and Vaclav answered that. Just one addition : I am not sure variable stiffness is the best approach here (though it had been partially implemented that way in some of the old contact laws). It is better to define the function "H(un) : un -> fn" so that the force is always exactly what it should be. Computing the derivative H' (stiffness) to compute H(un+dun)=H(un)+H'(un)*dun will only introduce approximation errors, and probably instabilities, and it is not faster. Defining the "current" stiffness H' would only help defining the critical timestep.
*//* */2) Is it possible to compact an assembly under a prescribed anisotropic stress state?/*
I'll let Luc explain his engine.
*//* */3) Is it possible to grow the size of a particle gradually?/*
Yes. See this function in TriaxialStressController.cpp (note you have to increase radii in bodies AND in interactions, as it's done in this function) :

/void TriaxialStressController::controlInternalStress ( MetaBody* ncb, Real multiplier )/
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