Mesh that fails on a tube triangulated beam

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Hello

The mesh is up to 32% and then fails.... I changed the size of the mesh but nothing helps...

Attached is the file.

Thank you in advance


poutre_6mx0.7_2.sldprt
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Hello Pierre,

To mesh and perform calculations on this type of part, the design method must be reviewed.

If you take 10 minutes to redraw it into "mechanically welded profiles " the mesh will be done in 1 or 2 seconds, and the results will be much more accurate

 

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Hello@pierre32

I think it's only due to the fact that in your selection your objects are in beam mode instead of volume.

The  beam mode is only valid for objects with a cross-section of more than 200 mm and/or provided that there is no machining on any profile.

In other words, your triangulated beam is not a beam (in the sense of the simulation), it is only a mechanically welded assembly using welded volumes.

So you have to declare all your profiles in Volume and everything will go back to normal.

Kind regards

PS: a stupid rule if your profiles are less than 200 mm in cross-section, use the volume mode, beyond that, use the beam mode provided that the profiles are not machined somewhere on the edges in particular.

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Thank you for your answers

Also, what is the difference - in design - between solid and mechanically welded?

And how to declare the beam in volume? "Combine" function?

Thank you

5

Re 

In other words, with what tools should this beam be modelled?

Thank you

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Knowing that there are 2 tube profiles and I can't manage the meetings between the groups in the mechanically welded well, am I clear?

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Good evening 

I have arrived at a result, phew, attached is the beam, if someone can take a look at it, in order to see the modeling mode, there is certainly faster and better -  DSL for the creation tree nothing is named.... Taken by the TPS....-

so the simulation was done, thank you in advance


poutre_6mx0.7__der.sldprt
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with the "Mechanically welded element" function you simplify your design and especially the calculations!

If you have two tube profiles, then you have to do the function twice.

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Hello @Pierre32

I looked at the way you did your simulation.

1°) Your simulation was carried out with Express simulation which is quite basic in these features. What I would indicate later only applies with SW Simulation premium. I don't use simu-express.

2°) it seems to me that you are making errors of reasoning

2a) in the manner of selecting the required movements

For the imposed movements, you put fixed geometries on both sides, so that it is the walls or equivalent structures that are supposed to be flexible. A beam is normally laid on a structure to allow for bending deformations. Otherwise, at least one side must be able to flex otherwise everything works in tears. If you attach one side, you should do it at the bottom of the beam and not on the end. The second side that supports the beam must be slippery so as to allow limited horizontal movement during bending.

Note : as we know nothing about the structure or the walls that support the joist, we cannot give the most suitable solution to take into account the bending at the end of the beam.

2b) in your choice of external loads.

You put a force when you should have selected a distributed mass. In addition, even when a distributed load is placed, it is imperative to know the MAX load to be supported. The big mistake that leads to dramatic accidents or even total ruins is to say that it supports a floor without specifying the load on it. For example, for a floor receiving people, it is 500 kg per m², whereas for projector supports in a theater it is not the same standards (100 kg per meter).

Finally, you do not specify any horizontal load or force. Because your beam is not triangular, you have no idea of the phenomena of buckling and spillage or rotation that could occur. It is prudent to clearly indicate all the movements that can act on the beam.

From my point of view, this simulation as it stands is false and should not be used to validate anything. It is necessary to specify the nature of the fixings at the ends of the beam and to better define the loads and especially the displacements (look at all the possibilities offered to take into account bending and sliding)

Kind regards

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Good evening zozo_mp,

First of all, thank you for your recommendations of kindness,

For this beam, it will support 6m2 of wooden floor with the joists installed in corbelling with notches capping the high tube, for the sides, between 2 wooden posts of 250/250 and 3 through bolts.

Also I was interested in the functions of the mechanically welded, simple efficiency and SW simulation rather than the express.

Thank you again to all 

Sincerely, Pierre

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Just a clarification in relation to the imposed movements "chosen" by Pierre: Simulation Express does not give any other possibility.

Personally, I cheat by limiting the blocked area (via separation line). I am perfectly aware that this is still a big approximation but it allows us to rough up certain cases.

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