topic Re: Seperate structure with solids in multipe directions in Robot Structural Analysis Forum

Seperate structure with solids in multipe directions

1234eddie — Mon, 02 Sep 2019 12:59:00 GMT

Hi All,

I’ve got a problem when i’m using solids. See the picture below, i got 2 contours(i create a face of them) which have to be extruded in the marked direction.

I have added a rigid support on the edges of contour 1. When i now run the analysis i’m getting the warning of seperate structure. I accept the warning and let robot continue, after that i get the instability warning. I have also accepted this warning. But when i check the result for just simple the dead load case i have unrealistic displacements on the solid created from contour 2.

The question is what do i need to changes or add to get these 2 solids connected?

I have also attached the pictures and robot models.

Thanks in advance.

Gr Edward.

Re: Seperate structure with solids in multipe directions

Krzysztof_Wasik — Tue, 03 Sep 2019 09:49:50 GMT

Hi @1234eddie

Before meshing connect both solids using

Edit >Edit solids and faces>Object combinations

Then mesh and calculate model

see attached file

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

Re: Seperate structure with solids in multipe directions

1234eddie — Wed, 04 Sep 2019 07:13:54 GMT

Thanks for your answer. This is clear for me now.

I got another question about solids, in particular if i have to model wood as solids(sometimes nessecary). In the pictures below are the contours which i all have extruded in the same direction.

The connection between 1 and 2 is just easy by using a simple bar between them and copy them a few millimeters in to the solids.(the connection can be seen as a screwed connection, with a little bit of space between the two parts).

But on the side of the extrusion this don’t work(connection between 2 and 3) how should i model this connection.

I’ve tried it with rigid links, and connect these to the front and backside of the extrusion. But this wil give weird stresses at the front and backside.

Or is it better to draw all six sides of the solid and create a solid from them?

Thanks in advance

Re: Seperate structure with solids in multipe directions

Krzysztof_Wasik — Wed, 04 Sep 2019 09:28:19 GMT

Hi @1234eddie

There is no good tool for this type of connections for extruded object side

We can try to divide contours before extrusion (like in attached file) but finally node position should be modified manually

Keep in mind that bar element has 6 degrees of freedom and solid element 3 degrees, so you cannot block bar rotation connecting it with solid elements only

Re: Seperate structure with solids in multipe directions

1234eddie — Thu, 05 Sep 2019 06:51:51 GMT

okay, thanks for your explanation. i'm aware of the 6 DOF's for bars and 3DOF's for nodes connected with solids.

a thought i have: should it work when i draw all six sides of the volumetric object as panels, and create then a solid?

(the only problem i have with this is that the volumetric object is not similar to a normal extruded object? is there something i did wrong?).

See attached pictures in zip file, left created all six sides(volumetric object 12), right created with extrusion(volumetric object 11)

Thanks in advance for your help. I really appreciate this.

Re: Seperate structure with solids in multipe directions

Krzysztof_Wasik — Thu, 05 Sep 2019 11:19:52 GMT

Hi @1234eddie

Using sides for solid creation you will be able to generate nodes at soil surface in desired place (where nodes will be defined) . It will not work inside solid.

Extruded and created from separate faces solids are represented in different way in object inspector.

Extrusion parameters can be modified by Edit >Substructure modification>Object modification while solids created from faces cannot be modified with that option