yade-dev team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

2010/3/26 Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>

>
>
>> Actually I defined the normal stiffness as secant and the shear one as
>> tangent. This because I was following PFC manual. But I see it is better to
>> get both stiffnesses as tangent (I will modify it). So once I do that I can
>> just pass those values to the GST, right?
>>
> GST will read kn/ks automaticaly. But be carefull, I'm not sure tangent
> stiffness is the best way for computing the force itself, it introduces
> approximations. The best would be to use an exact relation fn(un) for the
> force, like in PFC, and define the derivatives (and call them "kn/ks") for
> use in GST.
>
>
> Ok, thanks for suggestions. You could be right, I will think about that.
Actually for the normal direction I know where to look for (Hertz basically)
but for the shear direction I have not really understood the formulation I
found in PFC for the shear contact stiffness. Mindlin's paper seems
complicated, moreover he makes distinction between the case with or withour
slip, so that the tangential compliance changes. I will see to go into depth
cause I need this formulation.

cheers, Chiara


> Bruno
>
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