Re: [Getfem-users] Divergence of the first Piola-Kirchhoff stress tensor

[Huu Phuoc BUI]

Dear Yves,

Thank you very much!! It is working now.

Best regards,

Phuoc


On 14/07/2018 15:31, Yves Renard wrote:
> Dear Phuoc,
>
> I think the correct expression with Contract is simply
>
> div_sigma = "(Contract(Grad(first_Piola_Kirchhoff_stress), 2, 3))"
>
> Contract makes a summation with respect to the given indices, so that 
> Contract(A, 2, 3) = A_{i,j,j} with summation on j.
>
> Can your try again with the fix I commited to the master branch ?
>
> Best regards,
>
> Yves
>
>
>
> ----- Original Message -----
> From: "Huu Phuoc BUI" <address@hidden>
> To: "yves renard" <address@hidden>
> Cc: "franz chouly" <address@hidden>
> Sent: Friday, 13 July, 2018 12:00:55
> Subject: Re: [Getfem-users] Divergence of the first Piola-Kirchhoff stress 
> tensor
>
> Dear Yves,
>
> Thank you very much for your email.
>
> Please find enclosed a minimal code.
>
> I am not sure that I use correctly the Contract operator, you will find
> therefore both the original code and the new one for div_sigma:
>
> /div_sigma = "[Contract(Grad(first_Piola_Kirchhoff_stress)(1,:,:),1,2),
> Contract(Grad(first_Piola_Kirchhoff_stress)(2,:,:),1,2),
> Contract(Grad(first_Piola_Kirchhoff_stress)(3,:,:),1,2)].[1,1,1]"/
>
> Please let me know if you find the problem. Thank you!
>
> Best regards,
> Phuoc
>
> On 13/07/2018 08:59, Yves Renard wrote:
> > Dear Phuoc,
> >
> > No, a priori this should work. To simplify a bit your expression, you
> > can use Contract(Grad(...), 2, 3).[1,1,1] instead of the three traces
> > in div_sigma.
> >
> > If you give me a minimal code, I could have a look to the problem.
> >
> > Best regards,
> >
> > Yves
> >
> >
> > Le 12/07/2018 à 15:36, Huu Phuoc BUI a écrit :
> > > Dear GetFEM-users,
> > >
> > > As Grad(expression) is available in the new version of GetFEM++, I
> > > compute the divergence of the first Piola-Kirchhoff stress tensor as
> > > (python code):
> > >
> > > /div_sigma = "( Trace(Grad(first_Piola_Kirchhoff_stress)(1,:,:)) +
> > > Trace(Grad(first_Piola_Kirchhoff_stress)(2,:,:)) +
> > > Trace(Grad(first_Piola_Kirchhoff_stress)(3,:,:)) )"/
> > >
> > > in which first_Piola_Kirchhoff_stress is a macro of a model /md/,
> > > which is defined as:
> > >
> > > /md.add_macro("second_Piola_Kirchhoff_stress",
> > > "Compressible_Mooney_Rivlin_sigma(Grad_u, [c1;c2;d1])")//
> > > //md.add_macro("first_Piola_Kirchhoff_stress",
> > > "(Id(meshdim)+Grad_u)*second_Piola_Kirchhoff_stress")/
> > >
> > > Then I use generic assembly to assembly this quantity as:
> > >
> > > /eta_L_1_tmp = gf.asm_generic(mim,1,"(("+div_sigma+").delta)*Test_t",-1//
> > > //                             ,md//
> > > //                             ,"delta", False, mfz, delta//
> > > //                             ,"t", True,mfrj,np.zeros(mfrj.nbdof()) )/
> > >
> > > with /delta/ a given vector on a meshfem /mfz/.
> > >
> > > When executing the code, GetFEM++ only gives the error as
> > >
> > > /segmentation fault (core dumped)/
> > >
> > > If you see any problem in my code, please let me know. Thank you in
> > > advance.
> > >
> > > Best regards,
> > >
> > > Phuoc
> > --
> >
> >     Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
> >     Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
> >     20, rue Albert Einstein
> >     69621 Villeurbanne Cedex, FRANCE
> >     http://math.univ-lyon1.fr/~renard
> >
> > ---------