fem analysis

[ceschi1959]

my experience: 48 hours calculation for a simulation trying to characterize a plastic support with silicone over a glass....

to reduce the advisory time, where possible, of the artifacts such as to make a 'big' meshatura then go to apply the movements obtained around the meshate critical zones then in a more discarded way.

Hi.

 

[panormus]

days, years or minutes.. Who explains how to do catholic fem analysis, without great pretence? :biggrin:

we accept: notes, dispensers, links, tutorials, manuals, books,... :mixed:

 

[PierArg]

urca... tesi in informatica?

actually no. experimental physics-technological.
first I had to investigate a particular physical phenomenon that, until a few years ago, was not entirely known.
then I had to report the physical laws of that phenomenon in the "language" of computers to see if, at the computational level (ergo fem), the phenomenon could be deepened better.
I ran experimental tests.
then those fems.
I compared the results and, consequently, physical laws were officialized.

now those physical laws have become formulas recognized by the international community.all this only and exclusively to make you understand the importance of fem.

 

[Leonardo.G]

days, years or minutes.. Who explains how to do catholic fem analysis, without great pretence?

a good methodology of work consists in performing a first calculation using a linear coarse mesh to verify any errors due to incorrect imposition of constraints.
you then perform a second calculation using a finer, always linear mesh, paying attention not to overdo it by reducing too much the size of the item.
subsequently transform the elements from linear to parabolic.
Finally, the adactivity is used to refine the mesh in the most critical areas (by targeting the reduction of the current error) and an iterative calculation is performed by setting a minimum size value of the elements.

 

[panormus]

actually no. experimental physics-technological.
first I had to investigate a particular physical phenomenon that, until a few years ago, was not entirely known.
then I had to report the physical laws of that phenomenon in the "language" of computers to see if, at the computational level (ergo fem), the phenomenon could be deepened better.
I ran experimental tests.
then those fems.
I compared the results and, consequently, physical laws were officialized.

now those physical laws have become formulas recognized by the international community.all this only and exclusively to make you understand the importance of fem.

great pier compliments.
and for the cad3d community do you have something? :

 

[PierArg]

great pier compliments.
and for the cad3d community do you have something? :

thank you...but it was just to explain the usefulness of the fems, not my thesis:tongue:

Unfortunately I have nothing to teach the "good standards" of the fem simulation.
I used fems in a didactic way at university.
for work I do not use them ... I prefer to do everything pen/card and excel (also because the calculations are quite simple).
I rarely use the nx or elmer fem module but only to have a maximum idea of the phenomenon.

surely there will be textbooks explaining how to model mathematically (fem) a real problem with different cases and applications.

 

[Counterblow Hammer]

actually no. experimental physics-technological.
first I had to investigate a particular physical phenomenon that, until a few years ago, was not entirely known.
then I had to report the physical laws of that phenomenon in the "language" of computers to see if, at the computational level (ergo fem), the phenomenon could be deepened better.
I ran experimental tests.
then those fems.
I compared the results and, consequently, physical laws were officialized.

now those physical laws have become formulas recognized by the international community.all this only and exclusively to make you understand the importance of fem.

small deviation from the speech: what would the formulas in your graduation thesis refer to? . . .

 

[PierArg]

refer to the characterization of a particular phenomenon that is nothing but the superficial alteration of the material.
this happens in processes for removal of truciole (mainly milling and turning) at high speeds and with hard enough steels.


this particular layer is very clear in color and goes to inflate the mechanical characteristics of the piece.

 

[Tequila]

refer to the characterization of a particular phenomenon that is nothing but the superficial alteration of the material.
this happens in processes for removal of truciole (mainly milling and turning) at high speeds and with hard enough steels.


this particular layer is very clear in color and goes to inflate the mechanical characteristics of the piece.

told by a non Engineer what is that? cook the material superficially! ! !

 

[Counterblow Hammer]

refer to the characterization of a particular phenomenon that is nothing but the superficial alteration of the material.
this happens in processes for removal of truciole (mainly milling and turning) at high speeds and with hard enough steels.


this particular layer is very clear in color and goes to inflate the mechanical characteristics of the piece.

high cutting speeds and hard enough steels: It would seem, to the eye, to interest also the moldists this problem. Erro? . .

 

[PierArg]

the technical term is white and dark layer.

for several reasons, from the temperature generated due to friction with the tool, up to the high plastic deformations within a few moments, this happens:
- the surface layer "tempra" (it is very clear...white)
- the layer immediately after that tempered undergoes a "revenue" (it is darker...dark).
the model is able to defy the thickness of each of these two layers and its hardness.
the material on the outside is very hard, immediately after it is softer and in the heart (where not affected by the phenomenon) is a middle way.

to simulate 1 second of real process the pc used almost 2 days.

 

[PierArg]

high cutting speeds and hard enough steels: It would seem, to the eye, to interest also the moldists this problem. Erro? . .

the problem is very much felt on the turning...but it is also found on the processing of the molds.
I'm not experienced, but I think the molds are then polished once they're finished, right?

 

[Counterblow Hammer]

the problem is very much felt on the turning...but it is also found on the processing of the molds.
I'm not experienced, but I think the molds are then polished once they're finished, right?

Yes, it is correct!

So, in light of what you said now, the problem for moldists does not arise...

Perfect! was mere curiosity my... :finger:

 

[PierArg]

Yes, it is correct!

So, in light of what you said now, the problem for moldists does not arise...

Perfect! was mere curiosity my... :finger:

Please!
even if it is necessary to see if the polishing phase eliminates the whole layer "malvage" or remains a bit on the surface favouring the propagation of cracks.
the problem is that either you know how much you need to remove (micron order) or the only way to see the thickness of the layers is to dissect the piece.

This is why the fem, once the mathematical model has been characterized and validated, is also useful in the operational phase.

 

[Counterblow Hammer]

Please!
even if it is necessary to see if the polishing phase eliminates the whole layer "malvage" or remains a bit on the surface favouring the propagation of cracks.
the problem is that either you know how much you need to remove (micron order) or the only way to see the thickness of the layers is to dissect the piece.

This is why the fem, once the mathematical model has been characterized and validated, is also useful in the operational phase.

generalmete in polishing talk about the order of 50÷150 removed microns. . .

 

[PierArg]

Perhaps it could be that with the cutting speeds typical of the milling of the moulds and with the type of material we generate layers that are always eliminated in the polishing phase...it is because it is not much felt this phenomenon.

 

[Counterblow Hammer]

Perhaps it could be that with the cutting speeds typical of the milling of the moulds and with the type of material we generate layers that are always eliminated in the polishing phase...it is because it is not much felt this phenomenon.

more than for cutting speeds (now the trend of the moulders is to use high-speed cutting machines to lower the times) I would say that the repoble is not felt because polishing brings such a quantity of material to be eliminated the possible defectology mentioned by you (we talk about cents of depth of past against the microns of the thickness of the defect...).

more than anything, and of this I apologize, I had taken a quick conclusion before you exposed the problem: In fact, by reasoning to us the question I asked you was useless because its answer was implicitly contained in the statement "the molds are to be polished". ...

 

[panormus]

I wanted to understand a little more, but I didn't expect all this participation:biggrin:

If you want we can move to the post "surface quality" :smile:

 

[Counterblow Hammer]

I wanted to understand a little more, but I didn't expect all this participation:biggrin:

If you want we can move to the post "surface quality" :smile:

for me... so much these are healthy comparisons that only do well to both sides!...

 

[PierArg]

for me he can even stay here... he's just a little ot.

in the end it is served to understand how the fem was employed in this case.