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[Vincent Richefeu <richefeu@xxxxxxxxx>]

Le 4 janv. 2010 à 13:36, Václav Šmilauer a écrit :

>>> - with log, there is no upper limit to strain (except the grain 
>>> size/period size condition), you can compress 100, 200, 300%. With your 
>>> definition, e=100% has no meaning.
>> e=-100% ;-)
> (This BTW is not really "valid" argument... the same as that it would be
> better to use log(abs temperature) instead of temperature so that you
> can't get below 0K, or something similar for velocity so that you can't
> get above light speed. I still agree with you on that it makes more
> sense for compression to use log, though, and that the point is valid in
> general.)

Hi Vaclav and Bruno,

I've got just one short comment (it could help... or not...):
To avoid log, you could basically compute the natural strain as the sum of the increment strain at each time step.

eps = sum deps

so that (in 1D)

eps = sum  dl/l  /simeq dl/l0 for  small strain
                            /simeq log(1+dl/l0) for large strain

Vincent