Search found 195 matches

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...
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...
19 Jun 2012, 11:23
Forum: ElmerSolver
Replies: 13
Views: 7018

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...
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...
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...
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
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 ...
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...
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...
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...