## Search found 1071 matches

Tue Jul 09, 2019 6:54 am
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

4) The only case I can imagine where we could hit a similar issue with FreeCAD is when we load a part or structure with forces that exceed the elastic buckling load (but I would need to check the math of such a case to be sure) I can confirm this is the case. Analysis of a rigid column on a rotatio...
Mon Jul 08, 2019 11:43 pm
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

This is surprising and different from what I remember. I will look into it and compare to what I did for the bridge. great PS: yes the natural frequency in rad/s is the eigenvalue of the free vibration problem. than what is the column eigenvalue for? Do you know some paper which explains all this w...
Mon Jul 08, 2019 11:18 am
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

This is surprising and different from what I remember. I will look into it and compare to what I did for the bridge. great PS: yes the natural frequency in rad/s is the eigenvalue of the free vibration problem. than what is the column eigenvalue for? Do you know some paper which explains all this w...
Mon Jul 08, 2019 9:50 am
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

This is surprising and different from what I remember. I will look into it and compare to what I did for the bridge.

EDIT: the natural frequency in rad/s is the square root of the eigenvalue of the free vibration problem.

Sat Jul 06, 2019 2:18 pm
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

bernd wrote: Sat Jul 06, 2019 12:31 pm
HarryvL wrote: Sat Jul 06, 2019 12:19 pm I don’t understand. You have 5 values per line so the last one should be imaginary part in Hz as per my post.
no the number and four values ... see my screen from dat file !
Sat Jul 06, 2019 2:06 pm
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

Sat Jul 06, 2019 2:04 pm
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

Sat Jul 06, 2019 12:19 pm
Forum: FEM
Topic: extraction of negative eigenvalues
Replies: 35
Views: 2670

### Re: extraction of negative eigenvalues

- start FreeCAD - load FEM 3D example - change to analysis type frequency - change from first 15 to first 8 frequencies - delete constraint fixed and constraint force - run analyisis - the imaginary part in Hz is missing - screen and file attached test.FCStd Box_Mesh.dat.txt Screenshot_20190706_125...
Wed Jul 03, 2019 10:26 am
Forum: FEM
Topic: fcFEM integration with FEM work bench
Replies: 4
Views: 911

### fcFEM integration with FEM work bench

Further to https://forum.freecadweb.org/viewtopic.php?f=18&t=33974&start=170#p308524 here some notes for comment: Objective Provide practical finite element analysis capabilities within the FreeCAD framework that are easily maintained and extended. Characteristics Robust, automated solution ...
Wed Jul 03, 2019 6:34 am
Forum: FEM
Topic: Concrete branch ready for testing
Replies: 303
Views: 17748

### Re: Concrete branch ready for testing

Ah ok. Yes I didnt catch a potential NaN return from Calcilix, so that sounds like a good idea. However, anything downstream from this principal stress routine should be able to handle NaN values too. For example, what happens with this in VTK pipeline or VTK export?