Search found 195 matches

by mika
18 Oct 2012, 16:21
Forum: General
Topic: Beginner needs help.
Replies: 4
Views: 3774

Re: Beginner needs help.

Hi again, If the force per unit area is cumbersome to calculate, I believe that pointwise loads can also be specified by modifying the sif file as Boundary Condition k Displacement 3 Load = -10000 Target Coordinates(1,3) = 1.0 2.0 3.0 End Here the string before 'Load' ('Displacement 3') specifies th...
by mika
18 Oct 2012, 08:55
Forum: General
Topic: Beginner needs help.
Replies: 4
Views: 3774

Re: Beginner needs help.

Hi, Unfortunately the nomenclature used in Elmer in this connection may not be perfect. The keyword Force is actually used to prescribe a surface force per unit area which is usually referred to as the surface traction. In your setting the total force amounts to F = s * A where s is the prescribed s...
by mika
19 Jun 2012, 11:23
Forum: ElmerSolver
Topic: Elmer p-adaptivity
Replies: 13
Views: 7018

Re: Elmer p-adaptivity

Hi, Although Elmer offers ways to build discretizations based on p-elements, it is not guaranteed that all existing solvers support this option without modifying the solver code. By a quick inspection, I would say that the HeatSolve.src does not have a ready functionality for making p-discretization...
by mika
20 Oct 2011, 09:00
Forum: ElmerSolver
Topic: Neo-Hooke implementation
Replies: 17
Views: 11756

Re: Neo-Hooke implementation

Hi, I just committed a revision of ElasticSolve.src to enable the simulation of Neo-Hookean material. In this case, the second Piola-Kirchhoff stress is written as G = lambda/2 * (J*J-1) * Inverse(C) + mu * ( I - Inverse(C) ) with C the right Cauchy-Green tensor and J the determinant of the deformat...
by mika
04 Oct 2011, 08:19
Forum: ElmerSolver
Topic: Neo-Hooke implementation
Replies: 17
Views: 11756

Re: Neo-Hooke implementation

Hi, I returned for a while to this other constitutive model to see whether I am able to differentiate the constitutive law in a closed form. The differentiation was actually quite elementary, so developing the Newton iteration also for this model should be possible. Based on these exercises some mod...
by mika
08 Sep 2011, 16:10
Forum: ElmerSolver
Topic: Neo-Hooke implementation
Replies: 17
Views: 11756

Re: Neo-Hooke implementation

Hi,

The equation number (6.3) in my previous message should of course be (6.5).

-Mika
by mika
08 Sep 2011, 16:06
Forum: ElmerSolver
Topic: Neo-Hooke implementation
Replies: 17
Views: 11756

Re: Neo-Hooke implementation

Hi, First of all I would like to notify you that the documentation of the finite elasticity solver has eventually been done. I am attaching the relevant pages of the revised model documentation that concern finite elasticity. I hope that this limited piece of information helps in understanding what ...
by mika
01 Sep 2011, 18:33
Forum: ElmerSolver
Topic: Neo-Hooke implementation
Replies: 17
Views: 11756

Re: Neo-Hooke implementation

Hi, By exploring the code and taking the risk that I am not right, I would say that the finite elasticity solver treats the equations in the form where the constitutive equation describing the Piola-Kirchhoff stress is written as S = F G, with F the deformation gradient and G a response function def...
by mika
11 Jan 2011, 14:23
Forum: ElmerSolver
Topic: Memory allocation error & sementation fault
Replies: 16
Views: 8912

Re: Memory allocation error & sementation fault

Hi, I observed that applying BiCGStab(L) to a simple equation in combination with a highly accurate preconditioner may lead to a breakdown. This is indeed the situation in the stress computation here, so I expect that the NaN behaviour relates to this issue. I just committed a revision of IterativeM...
by mika
26 Apr 2010, 09:57
Forum: ElmerSolver
Topic: Convergence problem for smaller time steps!
Replies: 2
Views: 1930

Re: Convergence problem for smaller time steps!

Hi, There is a chance that this issue is related to a deficiency of standard stabilization strategies to cope with situations where the time step size is small in comparison with the spatial mesh size. A full discussion of this problem may be found at P. B. Bochev, M. D. Gunzburger and R. B. Lehoucq...