I am having a little concern about some data regarding shell forces component. As I am working on design of shell structures rebars, I need to calculate the forces and bending moments for each element of my structure mesh, initially using shell forces component. However, I thought about comparing these forces with an analysis on ABAQUS to see if the values are matching with eachother, which didn’t happen.
Firstly I noticed that the membrane forces in Karamba3d resulted in zero values while in Abaqus this didn’t happen. The bending moments also results in different values while comparing to Abaqus.
Would appreciate if someone could explain to me about these differences in calculations.
I’m going to paste a picture to ilustrate better. Here in the Pink group I joined the shell forces that resulted from karamba shell forces component and a FEM analysis in Abaqus, there we can see that the membrane forces (Nxx, Nyy and Nxy) are zero in karamba. The first question would be: why karamba forces are zero values whilst abaqus give me other results.
About the coarse mesh, it was a test when I was trying to figure out about this situation. Obviously we need the same mesh in both simulations so we can compare the results, I am not so worried about the values itself, but rather that the membrane forces are resulting in zero in all elements.
Don’t know if it is still confusing to understand my real question, if that is the case I can try to explain it in another way.
Dear @Vinícius_Gamboa,
The reason why membrane forces in Karamba3D appear as zero is that both the first- and second-order theory calculations assume small displacements. This results in a linear analysis, meaning that transverse displacements do not produce in-plane strains.
– Clemens
So there would be no way to get exactly the same values from Abaqus, right? I was trying to leave everything in the Grasshopper/Karamba3d environment so I wouldn’t have to import data.
But even so, I appreciate the explanation!!
Best regards,
Vinicius
Hello @Vinícius_Gamboa,
you could try the geometric non-linear calculation (see here). It is currently (version 3.1.5) work in progress. To use it you need to enable the WIP component visibility via the Karamba3D GH menu: Karamba3D/Show Components/View WIP Components.
– Clemens
