simulation of a complex frame

[gerod]

I am trying to understand the correct simulation method for structural analysis of a complex frame.
realize to take a hull of a boat and build the frame with tubes of various sizes.
Now, I tried to set the 3d in ansys ds but there are a number of problems on geometry and the mesh does not do it (the geometry has singular points or, being the tubes not perfectly combo, there are volumes that come up, etc.): the error is visible with the wireframe activated but I can't find it (they had put a visible flag!!!) also because we are talking in a frame of 30 meters x 15 x 1.5 and finding the millimeter that creates cases is difficult.
admitted that it can reconstruct the geometry and maybe arrange the joints between the tubes (the tubes join with skewer axes and therefore the union can give life to elongated -triangoli elongated surfaces - that give problems on the mesh).
the question: I was asked (from the dealer ansys) to use the mechanical version (I don't know which, but the version that also manages the beams).
some of you obviously will have used this form and therefore I would like to understand if it can actually go well to simulate frames but, above all, if it is simple to use or serves to make a course.
I never used it, so I don't know.

If the frames were regular I would have no problem in the simulation, I would do it with the ds structural version.
My fear of using beams is that I could lose some details on the joints, on some plates that have their interest in the calculation.

I can't put an example of the frame, top secret. imagine so many interlaced tubes that follow a profile of a hull.

Thank you.

 

[Fulvio Romano]

It doesn't seem like the best approach. If you have tubes, these are natural beams, a global beam pattern should be made, and it should be solved globally. then, if necessary, he modeled and studied the single joint with the structural, applying the loads coming from the global analysis.

making a global model with all the details of the joints makes everything very expensive, and often the results are little useful, or even little usable.

 

[gerod]

I agree, but I do not have the chance to do so today because my license is limited (I have no beam elements).
The approach is wrong, I know, but we must also understand what the tools are in the field.
the awfully expensive is there if geometry is hurt.
if it is built well, the thing is feasible.
we say that I want to understand how ansys works with such elements.
I found some tutoria, it doesn't seem so difficult

 

[Fulvio Romano]

the awfully expensive is there if geometry is hurt.
if it is built well, the thing is feasible.

mmhh. .
terribly expensive means that if I have a tube five meters long and often two millimeters, the mesh will have to be compatible with those two millimeters thick, instead of with the five meters, more natural.

 

[gerod]

Of course!
but then it is clear that the auction method is the best thing.
Now I wait for some ansys expert to give me some tips.
They would give me 1 free month for the upper license and so I have to optimize the times.
Thank you.

 

[Zaxxon]

hi gerod,
I have mechanical anxiety here and I have often used beams for complex frames. It's definitely the best and quickest approach, and the anesys also allows you to manage connections between beams and hull. We say that in a month you can make it complete the calculation. if you need some specific info let us know.

 

[gerod]

Thank you.
of frames I have several, some are simple and you can do quietly with design space from 3d.
others are complex (say 200-300 beams with knots put here and there).
a question: my beams, as I said, are beams that are rotated in space. ansys allows you to position the beam so that the main axes of the beam section are also rotated compared, for example, to the main coordinate system?

 

[Zaxxon]

ansys beams have their own coordinate system, it is created with the item just to properly orientate the section.