31. Model generation in Blender

Questions and discussion for this lecture live here. Fire away by hitting Reply below :fire:

Hello Sean,

I hope this email finds you well. I’ve been grappling with a question for quite some time now, and I’m hoping you can shed some light on it.

When it comes to designing a cable net structure, we often employ tools like Blender for the initial form-finding process. This entails determining the structure’s shape, taking into account factors such as gravity and specific pretension. Once we have the initial shape from Blender, we proceed to use our FEM solver for further analysis.

Here’s where my question arises: The initial shape obtained from form-finding in Blender inherently incorporates stresses and reactions due to the applied forces. However, when we carry out the analysis using the FEM solver, it assumes the initial shape to be stress-free. This discrepancy concerns me.

To address this issue, I’ve been contemplating starting the analysis with a different initial shape that accurately matches the shape obtained from Blender under the influence of gravity and pretension. By doing so, we ensure that the analysis engine considers the existing stresses and reactions present in the structure from the outset.

Sean, I would greatly appreciate it if you could provide some clarification on this matter. Am I on the right track with my thinking? Your insights would be invaluable.

Thank you for your time and assistance.

Best regards,
Tien

Hi Tien,

We address this in lecture 38 - have a look at this and see if it answers your questions. If not, follow up with me.

Cheers,
Seán

Hi Sean,
If I start with a “starting point” shape from Blender, and then apply self-weight to find out the tension profile in the net, how is this related to the actual construction of the structure?
For example, after analysing with self-weight, I got perimeter cables having, say, 10kN tension in them, when we build the cablenet, do we initially pretension these perimeter cables or not?
I am a bit confused here.
Tien

Hi Tien,

I’ve addressed in the thread for lecture 44.

Cheers,
Seán