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Re: Elastic energy

 

FYI, energy is conservated almost exactly in a periodic triaxial test (taking into account also the work input from boundaries). I just checked. It seems errors come only in dynamic bouncing spheres, I hope you'll find the problem folk!

Bruno

chiara modenese a écrit :


On 5 July 2010 10:07, Janek Kozicki <janek_listy@xxxxx <mailto:janek_listy@xxxxx>> wrote:

    Janek Kozicki said:     (by the date of Mon, 5 Jul 2010 01:26:08
    +0200)

    > where U_tot is shearDisp. I may be wrong, though - just an idea.
    > The graph is still  wrong, but it looks a little bit better.

yes.. I know that this is wrong. Yes Janek, it is wrong because u_tot in the equations I wrote is an increment (note the dot over the letter u). We agree that it must be an increment and that the formulation has to be incremental.
    But maybe we could identify what assumption is wrong if we find
    the answer: why with this modification the graphs are better? The
    plastic dissipation doesn't go through the
    roof, but actually looks like an averaged value of what it should be.

I do not know yet. I am playing with this, please do let me know if you find an explanation.. I am having exaclty the same problem with the non linear law HM, where I worked out all the contributions (even the elastic ones) incrementally (trapezoidal rule). Again with no friction seems fine, but if sliding occurs then plastic dissipation increases dreadfully. Why??


    Did you notice that kinetic energy becomes too high just after the
    friction angle is set to 25?

    --
Janek Kozicki http://janek.kozicki.pl/ |

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--
_______________
Bruno Chareyre
Associate Professor
ENSE3 - Grenoble INP
Lab. 3SR
BP 53 - 38041, Grenoble cedex 9 - France
Tél : 33 4 56 52 86 21
Fax : 33 4 76 82 70 43
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