Search found 155 matches

by mika
18 Apr 2020, 17:19
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

are there any reasons why Spring 4 is rotation Y instead of X? is it the same syntax to include mass points? Springs and DOFs are enumerated in the same way. To understand the enumeration, the "rotational" DOFs should not be thought of as (approximate) rotations, but in the first place they just gi...
by mika
17 Apr 2020, 15:56
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

When looking at this, I found that the (mass) moments of inertia were computed erroneously by the shell solver. The effect was an erroneous multiplication with the thickness h. This has been corrected in the devel version today so that the elementwise contributions to the rotational mass matrix now ...
by mika
16 Apr 2020, 16:29
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

perhaps you can point out where I am going wrong. - In section Solver 1 add (to replace the default component names of the shell solver) Variable = U - In section Solver 2 change Displacement Variable Name = U - In section Solver 3 remove Vector Field 1 = String eigenvector Then I get output. -- Mika
by mika
16 Apr 2020, 16:06
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

For generating vtu output in the case of eigenanalysis see the example eigenanalysis.sif at

https://github.com/ElmerCSC/elmerfem/tr ... s_Cylinder
by mika
16 Apr 2020, 14:06
Forum: ElmerGUI
Topic: [Magnetostatic] different results for FEMM and Elmer
Replies: 2
Views: 448

Re: [Magnetostatic] different results for FEMM and Elmer

I'm not familiar with FEMM. Anyhow, how sensitive is the result with respect to the BC on the outer surface or on the location of this surface? Do the two models have the same BC on the outer surface?

-- Mika
by mika
16 Apr 2020, 13:50
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

To target nodes for these boundary conditions I believe they have to be boundaries in your mesh.boundary file. I would like to recall that if one wishes to add springs (or masses) by using a group identifier of 1-dimensional elements (nodes) as Boundary Condition X Target Boundary(1) = ... Spring 1...
by mika
15 Apr 2020, 16:38
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

In the sif file Young's modulus is defined as

Youngs modulus = 1.0e16

This large value must be in some unexposed system of units or is likely to be unphysical if in SI units?
by mika
14 Apr 2020, 14:59
Forum: ElmerSolver
Topic: Structure Analysis with both Beam and Shell elments
Replies: 16
Views: 1434

Re: Structure Analysis with both Beam and Shell elments

I used some hours for this and wrote changes to the shell solver so that the shell solver can also assemble and solve a pure beam model, obsoleting the separate solver for the beam equations basically. However, in my earlier comments I ignored an issue which makes the DOFs of the shell model and the...
by mika
14 Apr 2020, 10:48
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

As already discussed, the shell element needs some constraint to resist rotation around the normal to the shell mid-surface. The remaining zero-eigenvalue should be due to the lack of such constraint. With Elmer the only way to exclude the rotation around the shell normal is a sufficient number of c...
by mika
14 Apr 2020, 01:41
Forum: ElmerSolver
Topic: Introducing springs to a point/face as a boundary condition
Replies: 62
Views: 3094

Re: Introducing springs to a point/face as a boundary condition

Oops, forget my previous message about minimal conditions to prevent rigid displacements. A combination of translational and rotational DOFs constraints should of course do as well.

-- Mika