Are there additional "arrays"? what about unaveraged results?


#1

Hi,

  1. Regarding results - I only see options to show a few results “fields” (von mises, strain etc), where can I find additional results (principal stress, force reactions, etc.)?

  2. What about averaged and not averaged results? from what I saw, all the results are averaged, is there an option to show unaveraged results?

Thanks.


#2

Salut @assafwei,

regarding your first question you can add additional output results manually (see picture).

I am also interested in an easy solution to seperate between averaged and non-averaged. :smiley:

Cheers,

Jousef


#3

Hi,

Thanks for the quick answers. I will try adding manually, see what I can find there.
Regarding averaged / non averaged visualization - I think it is a very basic functionality of a FEA post processor - this is the main and easiest way (to me at least) to check if the results are OK, if there are irregularities in the stress results and so on.
I understand there is a possiblity to export the results to paraview - will the unaveraged results be available in paraview? did you try it (Im not very familiar with paraview, this is something I am trying to get to for a long time now…)

Thanks.


#4

Hey @assafwei!

You can give more solution fields by going to Result Control and then Solution fields where you can add more solution fields yourself. There are several solution fields available for advanced solvers.

I am not sure if you are asking here about the results on some specific entity or as solution field. For the former one you can use the data plotting feature on certain entity under Result Control (this feature is only available for the advanced solvers). For the solution fields, please see the above answer.

I hope this helps. If you have any question/s, feel free to ask.

Best,
Ahmed.


#5

@jousefm @ahmedhussain18

What @assafwei is asking are the un-averaged field solutions. This are located in the integration points of the elements, and are also known as Gauss (quadrature) points. This are the points where the solution is actually calculated before being averaged to the element’s geometric center and then to nodal points. Thus, one can have the solution fields expressed in three discrete point sets:

  • Integration (Gauss) points: non averaged results.
  • Elements geometric center points: once averaged results.
  • Nodal points: twice averaged results.

Notice that the nodal solutions have some errors added to them by the averaging process, that is why it is important to check the other solutions when analyzing results.

I searched and couldn’t find a way to get this results printed in the solution fields available for posprocessing. I know for sure that they are calculated by the solver, guess they are discarded to save memory.


#6

Hi @ggiraldo

This is exactly what I meant, not only that the error is smaller with non averaged, but the most important thing is that when viewing the non averaged stress / strain plots it is very easy to see if there are any discontinuities in the stress / strain field - which indicates bad discratization of the geometry / poor BCs, this is one of the main tools that I use to find out if my model is properly discretized, and as you said - this must be computed during the solve process and should be available.


#7

Hello @ggiraldo @assafwei,
you are right, you get a better picture of the results when looking at the elemental and Gauss point data but in most (reasonably meshed) cases the averaging errors are negligible compared to the other error sources.

This feature is definitely on the road map and technically not very hard to implement (at least for the Code_Aster based analysis types). Considering that the result size would be multiplied by a factor of 3-20(!) if we would by default compute and write all fields on the three different locations, would you rather have them computed automatically for each field or only per user request, for example as an additional setting in the solution fields selection?

Best,
Richard


#8

Hi @rszoeke, can I have my cake and eat it too? Ideally I would like to be able to run the simulation with the minimum number of results fields, then, if I would like to investigate further, I could rerun the simulation, but just to calculate additional fields and add them to the available results (without doing the full solution all over again).

If that is not an option then I would opt for user defined fields (as opposed to getting everything by default).

Regards, Ben


#9

Sure :wink:

In principle this can work and already have the request to “restart” and already done run, especially for fluid mechanics simulations. There it is very common in a not-yet-converged stationary analysis to restart it (possibly with modified parameters) to do some more iterations until convergence.

This is would need a rather big development effort as it contradicts our current paradigm that a simulation run is immutable. This could be overcome by chaining simulation runs, using the previous one as initial condition for the new run. This is on our road map already, but nothing for short term release.

The solution with the user defined fields would be a rather quick solution. It’s already on the feature request list and starting to increase its priority :wink:

Best,
Richard


#10

@rszoeke

I support the additional options in the user requested fields, to include fields on integration and element points.

The processing of the results to calculate new fields without solving the whole problem again would also be really good, specially to save on core hours.