yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 10 May 2010 18:23, chiara modenese <c.modenese@xxxxxxxxx> wrote:

>
>
> On 10 May 2010 18:03, chiara modenese <c.modenese@xxxxxxxxx> wrote:
>
>>
>>
>> On 10 May 2010 17:43, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:
>>
>>>
>>>
>>>> Hi Bruno, please see attached file. I am not completely sure but I think
>>>> it would be correct to distinguish between loading and unloading phase. I am
>>>> trying to prove it analytically, I am not yet totally confident.. What do
>>>> you think?
>>>>
>>>>  There is no trialFs in your figures, this is the key factor.
>>>
>>> us + (current-prev)/ks could make sense in some formulations if *=ratio
>>> was applied _before,_ but it is applied _after, _so that "current" is in
>>> fact the "trial" value (as you pointed out).
>>>
>>> OTOH, us is exactly (trialFs-prevFs)/ks, by definition of trialFs,
>>>
>> btw, us as you intend here is actually the total plastic displacement, not
the incremental one. My delta_us I was referring to is an incremental one
(and to me we need an incremental formulation here).


> (trialFs-currentFs)/ks is exactly the plastic part ,
>>> and (currentFs-prevFs)/ks is the elastic part.
>>>
>>> I don't see any difference between loading and unloading.
>>
>>
>> I agree that the plastic displacement is (trialFs-currentFs)/ks. However
>> your formulation is not incremental because you are using the trial value.
>> To me this would be the right procedure only in the case in which shearForce
>> is maintained constant. But shearForce is actually varying (right? Where do
>> you account for this variation in your formula?) and as I sketched in my
>> picture there is an elastic contribution that turns into plastic
>> dissipation. Can you see my point? I will find out the analytical
>> explanation.
>>
>>
> When I say shearForce is varying I mean the maximum friction value. Maybe I
> am a little confused now, perhaps I am wrong. Could you just tell me if you
> see any effect due to the variation of the maximum friction? Because that is
> why I was making distinction between loading and unloading and for the same
> reason I am not convinced that using Trial force would be the best choice.
> thanks, chiara
>
>
>> Chiara
>>
>>>
>>>
>>> Bruno
>>>
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>>
>>
>