Karamba3D

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Comment by jiaxing on March 22, 2020 at 9:16am

another questions about the initial strain load,  from the cases provide, for example,the beam with initial strain load  do not have shear force and bending monent. in my understand , pure axis force only  is much more safe then  shear force, bending moment, and axis force together(hope my understand is right)

not sure my understanding is right:  this initial load is the results of axis-force we want it inside and a load affect.

my question is, 1. in reality projects  where does this load come from? it is the results of load we want. then how to add this on?

2. if we can use initial strain load  to replace other loads, then how to transfer other loads with initial load. for example  the beam under gravity become an arch, but we want a pure axis force arch, no shear force,  then how to transfer gravity G=10 equals  initial strain load?

3 is there any case of projects use initial strain load help me understand? 

Comment by jiaxing on March 19, 2020 at 10:54pm

hi, clements, thank you very much for your answer.

I learn this case about mesh load  and have 3 questions

1. there are meshs and beam, but the mesh do not have material , only have load,  what is that?

2. the mesh is not attached to beam, how to understand it?

in my understand the case is , for examble, mesh is floor , have dead load or live load, then under floor is attached beam,  this floor and beam should have intersect part, then the load will transfer to the beam.   but here, they are seperate.

3, the mesh load is z-direction, but it turns a x-direction affect on beam, why

pls help,  i know you help alot already

keep safe from virus  hope vienna is ok

jiaxing lu 

Comment by Karamba3D on March 18, 2020 at 10:08am

Hi, Jiaxing,
the eigenmodes and eigenvalues result from the solution of the eigenvalue problem (see e.g. here) of the stiffnessmatrix S. The eigenmodes show in ascending order those deformation modes which the structure can take on most easily. The eigenvalues are the ratio between the internal forces and the corresponding eigenmode displacements.
The eigenvalues and eigenshapes as calculated in Karamba3D have nothing to do with stability or vibrations. For the buckling modes one has to solve the general eigenvalue problem which involves the stiffness matrix and the geometric stiffness matrix. For the vibtration modes it's the general eigenvalue problem involving the resultant stiffness and mass matrix.
-- Clemens

Comment by jiaxing on March 17, 2020 at 10:19am

hi, clements,  i read karamba manual again,  during that, the eigenmode and eigenvalues still troubles me to understand,  it seems to test vabration and get eigenvalues by eigenmode. 

what is the funcion of eigenmode, and what does the eigenvalue mean?

stability?  do the eigenvalues has standard to show whether it is safe or not?

sorry,  it seems a basic structure knowledges,  

Comment by riccardo foschi on February 11, 2020 at 2:39am

right sorry for that, and thanks

Comment by Karamba3D on February 11, 2020 at 2:03am

Hi, I am moving all discussion to the user problems page as the parallel discussion is cumbersome. https://www.grasshopper3d.com/group/karamba3d/forum/topics/karamba-...

Comment by riccardo foschi on February 11, 2020 at 1:35am

It turns orange because I set one point as support two times (it's part of two groups of points one group fixes the Z movement the other one fixes every movement), but it shouldn't be a problem right? at least the dialog box says so.

Anyway the problem is similar if I decimate the mesh, I think it might be a problem of how do karamba calculate the thickness of the structure, in fusion I modelled the thickness myself in Karamba I didn't maybe it's that? however I think in fusion when he calculate the mesh he also adds inside edges to keep the two layers together when deforming, in karamba I don't think it does it am I wrong?

Comment by Karamba3D on February 11, 2020 at 1:27am

Hi Riccardo, there seems to be an issue with you definition as it turns orange. Also, may it be that your mesh is too coarse?

Comment by riccardo foschi on February 10, 2020 at 10:12am

Another question: I'm trying to reproduce the behaviour of these two structures that I observed in fusion 360 only using Karamba.

As you can see from the images the structure on the left have much less deformation, in Karamba they are almost the same what is happening here? The KAramba code is so much different from the fusion 360 one?

Comment by Karamba3D on January 7, 2020 at 1:28am

Dear xiufeng li, when internalizing structural objects in one version of Karamba3D it is sadly not possible to guarantee that they can be deserialized with another version of Karamba3D. I think this is what causes the problem here.

Best,

Clemens

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