|Subject:||Re: [Getfem-users] Displacements are mesh-size dependent in a simple 2D linear elastic problem?|
|Date:||Tue, 16 Dec 2014 17:42:11 +0100|
|User-agent:||Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0|
Yes, normal_of_face_of_convex gives a normal vector which lenght is the determinant of the transformation from the reference face on the real face. However ... the area of the face of the reference element depends if it if a face parallel to an axis (lenght 1) or the third face wich is of length sqrt(2). So the length of the normal vector is not directly the area (length) of the face.
If I understand well, you want to compute the equivalent forces on each face corresponding to your uniform pressure.
One simple way to obtain the lenght/area of a face (even for curved ones) is to sum the weights of an integration method on the corresponding face multiplied by the determinant of the transformation (i.e. to integrate 1 on the face). If you do not want to go to the internal of getfem, you can simply ask to compute the mass matrix between a P0 finite element method (eventually reduced to the boundary you look at) and a finite element on which you define the pressure. Or if you use the high level generic assembly, you can simply ask the assembly of the term "-Normal*Pressure*Test_p0" on the corresponding boundary where Pressure is your contact pressure and p0 is a field defined on a P0 finite element method.
Concerning the displacements, what do you mean by "I calculate the resulting displacement ?". You calculate some displacements explicitely from the computed force on each face ? I do not see very well how you can do that. Could you explain more this point ?
Le 15/12/2014 16:32, Tom Haeck a écrit :
-- 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 ---------
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