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Re: need your help

  • To: mathgroup at smc.vnet.net
  • Subject: [mg118410] Re: need your help
  • From: Oliver Ruebenkoenig <ruebenko at wolfram.com>
  • Date: Wed, 27 Apr 2011 05:38:25 -0400 (EDT)

On Sun, 24 Apr 2011, Arezoo Sadrinezhad wrote:

> Hello Mathematica Friends,
>
> I am stuck with this problem, where I use NDSolve[] to solve a partial
> differential equation.
>
> The error is: NDSolve::ndnum: Encountered non-numerical value for a
> derivative at t==0!
>
> The sample code is below.
>
> Please suggest me ways to solve this problem. Thank
> you.
>
>
> --
> Best regards,
>
> Arezoo Sadrinezhad
> Ph.D. Student
> Department of Civil Engineering
> University of Akron
> Akron, Ohio 44325-3905
> Email: as144 at zips.uakron.edu <mailto:as144 at zips.uakron.edu>
>
> This is my code:
>
> AC11=10;
>
> AC22=5;
>
> DC1111=25;
>
> DC2222=6.25;
>
> LB=-0.06;
>
> RB=0.1;
>
>
>
> StressIC[s11_,s22_]:=Limit[(1/((2Pi)*c*c))*Exp[-(1/2)*(((s11-0)/c)^2+((s22-0)/c)^2)],c->0.001];
>
> Plot3D[StressIC[s11,s22],{s11,-0.1,0.1},{s22,-0.1,0.1},AxesLabel->{"sigma11","sigma22","P[s11,s22,0]"}]
>
>
>
> YieldStressDistribution=NormalDistribution[0.05,0.5*0.05];
>
> CDF[YieldStressDistribution,h]
>
> Plot[CDF[YieldStressDistribution,h],{h,-0.2,0.2}]
>
> YF[s11_,s22_]=Abs[s11-s22];
>
> cumuldist[s11_,s22_]=0.5*(1+Erf[28.2843*(-0.05+YF[s11,s22])])
>
> Plot3D[cumuldist[s11,s22],{s11,-0.4,0.4},{s22,-0.25,0.25},PlotRange->All]
>
>
>
> AC11p[s11_,s22_]=AC11*(1-cumuldist[s11,s22])
>
> AC22p[s11_,s22_]=AC22*(1-cumuldist[s11,s22])
>
> DC1111p[s11_,s22_]=DC1111*(1-cumuldist[s11,s22])
>
> DC2222p[s11_,s22_]=DC2222*(1-cumuldist[s11,s22])
>
>
>
> ElasticPlasticEq={D[AC11p[s11,s22]*P[s11,s22,t],s11]+2*D[AC22p[s11,s22]*P[s11,s22,t],s22]+D[P[s11,s22,t],t]-D[DC1111p[s11,s22]*P[s11,s22,t]*t,{s11,2}]-2*D[DC2222p[s11,s22]*P[s11,s22,t]*t,{s22,2}]==0,P[s11,s22,0]==StressIC[s11,s22],
>
> AC11p[LB,s22]*P[LB,s22,t]-(D[DC1111p[s11,s22]*P[s11,s22,t]*t,s11]/.
> s11->LB)==0,
>
> AC11p[RB,s22]*P[RB,s22,t]-(D[DC1111p[s11,s22]*P[s11,s22,t]*t,s11]/.
> s11->RB)==0,
>
> 2*AC22p[s11,LB]*P[s11,LB,t]-2*(D[DC2222p[s11,s22]*P[s11,s22,t]*t,s22]/.
> s22->LB)==0,
>
> 2*AC22p[s11,RB]*P[s11,RB,t]-2*(D[DC2222p[s11,s22]*P[s11,s22,t]*t,s22]/.
> s22->RB)==0}
>
> Off[General::stop];
>
>
>
> t=.;
>
> ElasticPlasticSol=NDSolve[ElasticPlasticEq,P[s11,s22,t],{s11,LB,RB},{s22,LB,RB},{t,0,0.03},
> StepMonitor:>Print[t],SolveDelayed->True]
>
>
>
> I would be really grateful if you could help me! I really get stuck.
>
>>
>> On 04/23/11 18:01, Arezoo Sadrinezhad wrote:
>>
>>>  Hello Mathematica Friends,
>>>
>>>  I am stuck with this problem, where I use NDSolve[] to solve a partial
>>> differential equation.
>>>
>>>  The error is: NDSolve::ndnum: Encountered non-numerical value for a
>>> derivative at t==0!
>>>
>>>  The sample code is attached to this email.
>>>
>>>  Please suggest me ways to solve this problem. Thank
>>>  you.
>>>
>>>
>>> --
>>> Best regards,
>>>
>>> Arezoo Sadrinezhad
>>> Ph.D. Student
>>> Department of Civil Engineering
>>> University of Akron
>>> Akron, Ohio 44325-3905
>>> Email: as144 at zips.uakron.edu <mailto:as144 at zips.uakron.edu>
>>>
>>
>
>
>

Hello,

I can not reproduce the error message: I get the following

  NDSolve::delpde: Delay partial differential equations are not 
currently supported by NDSolve

Oliver


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