yade-dev team mailing list archive

[Václav Šmilauer <eudoxos@xxxxxxxx>]

> Hehe. There is a french saying like "the world is small" (le monde est 
> petit).
in czech it exists also (svět je malý) :-)

> Yes for the product. The tricky part is defining "strain" is not 
> straightforward, it is easier to consider it as a result of the integration.
> In order to keep a complex case in mind, you can imagine a rotational 
> "strain" (in fact disp/vel gradient) with exy=-eyx=pi/100 rad/second. 
> After 100 seconds, Hsize will be
> 
>  0,y₀,0   
> -x₀,0,0 
>  0,0,z₀
I am curious if the collider would survive that, because of the 1/cos(φ)
factor for spheres... (We could figure way to transform Aabb as well,
e.g. by using (normalized) columns of Hsize as base of the Aabb space,
then the Aabb would be enlarged only for shear, not rotation; complex
thing, though.)

> If the code can handle this, then we can consider it general enough 
> IMHO. The diagonal multiplication cannot do that probably.
I am wondering what is cell rotation good for, though...? If you rotate
the cell, it doesn't change the sphere arrangement or contact forces or
displacements in any way.

> > 5. Way to directly prescribe cell normal&shear strain (like what the
> > strain matrix has now).   
> One way could be to add members like this :
> 
> void setStrainRate(int i, Real value) {gradVel[i][i]=value;}

See in the other mail. I meant rate of all "strain" (think trsf)
components, to get puse shear etc.

v