topic Re: Node instability (type 1) issues in Robot Structural Analysis Forum

Node instability (type 1) issues

DavidEEP — Mon, 03 Jun 2019 11:00:46 GMT

Hello!

I am starting using Robot for all my designs.

I am trying to design an roof enlargement for a building and I get multiple warnings for node instability (type 1) in all directions for all the nodes in a wall. I don't understand why. Is there a catch with realeases, with the unisotropic materials for the wall sections? Can you help me, please?

If I use another structural designing software and do the the same, I am getting the results without any issue...

Re: Node instability (type 1) issues

Rafacascudo — Mon, 03 Jun 2019 12:24:11 GMT

some of your "CLT 100 C3s" walls(those with instable nodes) are on XZ plane ,so the main orthotropy direction for these walls must be either on X or Z direction. But you defined Y global direction as main orthotropy direction.

Correct it and it will work

Re: Node instability (type 1) issues

DavidEEP — Mon, 03 Jun 2019 12:31:45 GMT

Thanks. I will try.

So if I am right, the orthotropic direction is defined in the Global CS, is it?

Re: Node instability (type 1) issues

Rafacascudo — Mon, 03 Jun 2019 12:54:36 GMT

it can be in any direction , but ,yes, based on the Global CS

Re: Node instability (type 1) issues

DavidEEP — Mon, 03 Jun 2019 13:12:59 GMT

I did it as you said, and all the instability (type 1 ) warnings disapered, but I still don't reach the right results.

Now I get a node instability (type 3) warning for Uy everytime in different node.

Thank you in advance for your help.

Re: Node instability (type 1) issues

Rafacascudo — Tue, 04 Jun 2019 12:53:30 GMT

1- You have no loads assigned for load case 1.

2- Search forum for instability type 3 warnings . There are thousands of messges about. Seems to be fake in your case.

3- your mesh is not good on 2 spots . check your panel/bar geometry