Hinge joints between meshes

Grasshopper Karamba3D
1

Hello. I am trying to simulate some meshed panels connected by linear hinges. I am trying to model the linear hinges as a series of points aligned along the desired hinge, with all 3 rotations free. This should produce the same movement. I made 3 cases. Case 1: meshses are separated by zero-length beams modelled as springs (almost null rotational stiffness, high translational stiffness). Case 2: points shared by the meshes (ie points along the desired hinges) are plugged into the beam-joint component, with all their rotations free, all translations blocked. they should act as a linear series of spherical joints, thus producing the linear hinge. Case 3: this is just a reference case, I do not have joints and I combine all the meshed panels into a big mesh. Now, Case 3 and case 2 give me the same deflection under load. So, does beam-joints work with meshes? Or what could be wrong?
sketch

2

Hello Valbe363,
beam-joints work with meshes. Here is an example: Shell_LinearHinge.gh (42.3 KB). It works with Karamba3D 1.3.2.

Best,
Clemens

3

Hi Valbe363 and Clemens,
I am using springs to model a segmented shell. I started from the example file you posted in this thread, hence posting it here, apologies if it should be a new thread…

I think everything is setup correctly (we all do right?)
multiple shells in karamba 04 gapREDUX.gh (72.5 KB)
However I am getting a weird result: the lines that represent the spring beams in model view are very long (first image below), extending way beyond the lines that were used as input to LineToBeam (in green in second image below)

overview
overview1566×638 93.6 KB

zoom
zoom1565×638 114 KB

Any ideas on why this is happening?
I’m still trying to assess if the results are as expected, in which case this would just be an annoying aesthetical bug, but something tells me it’s more than that…

Thanks in advance for your feedback,
Eduardoe

4

Hello @castroecosta,

I have to check why the springs are not displayed correctly.

For modeling line-joints there is now a better option in Karamba3D 2.0.0 WIP (see here): the Line-Joint component. Its UI will be further improved in the next WIP releases but it can already be used. In the examples which come in the installation folder of Karamba3D you will find two definitions which show how to apply it.
– Clemens

5

Thanks Clemens.
Although I ended up not using line-joints, I am enjoying other new features in 2.0.0 WIP.