Week 7: Karamba Testing the Grid

We need to find out how many members are needed to make the grid stand. We want to use a less as possible to:

• Save material/money
• Make the structure look less cluttered

I made a grid using a tutorial I found on the internet as the parametric grid given to me would not work in Karamba.

Shown above is the grid I was given, it would have errors in relation to its supports and would continuously crash when I would try to make it work by playing with parameters etc.

I made a grid using points and lines and came up with this.

I then plugged the grid into the script I worked out before (creating and testing beams in Karamba) just to see the reaction. I received this error.

There are 90 rigid body modes in the system. This means some parts can move freely without causing deformation.

Try to use the ‘Eigen Modes’-component and activate the display of local coordinate axes: The first eigen-mode will be the rigid body motion.

If this does not help, check whether you have a pinned support directly attached to a hinge. A hinge introduces an extra node which may cause the problem.

When analyzing a flat shell structure one has to lock the rotation perpendicular to the plate in at least one node.

I did as suggested and added the ‘eigen-mode’ component and received the same error.

After reading forums, I understood that this error mean’t that this grid was kinetic, and can move without deforming. This can be because of not enough supports or when a system is not properly connected.

I decided to run the analysis through one beam, to see if it would work.

Error States:

There are 3 rigid body modes in the system. This means some parts can move freely without causing deformation.
Try to use the ‘Eigen Modes’-component and activate the display of local coordinate axes: The first eigen-mode will be the rigid body motion.
If this does not help, check whether you have a pinned support directly attached to a hinge. A hinge introduces an extra node which may cause the problem.
When analyzing a flat shell structure one has to lock the rotation perpendicular to the plate in at least one node.

I knew that it was connected, as it was one line. So I looked at the supports to find I had not locked the conditions into place to make a fully fixed structure.

After doing this, I ran it again and it fixed the error.

I put all the lines back into the ‘line to beam’ function and made all of the beams fixed and achieved a script with no errors.

I played around with the sliders for the step size and count size to receive the same level of displacement.

After collaboration with other groups, I came to my attention that I had done the supports wrong. I only needed supports on the ground, and only the ‘T’ conditions needed to be locked. I was also told I should be looking at this structure using the utilization render view.

I again, fixed the issues and got the following result.

Red = Compression

Blue = Tension

Obviously, the aim is to get these values as small as possible. The render also shows there is a lot of stress around the 0,0 point. My group and the other thought it might be something to do with a double up of lines or the way I’ve made the whole grid.

I fed all the lines through the ‘remove duplicate lines’ components and it found no duplicates. Catherine then pointed out that this issue could be due to the horizontal beams stretching out beyond the verticals ones.

I fixed that issues and received a utilization factor of 10%.