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Lacking reliability of the Solid Edge Material Table?

Genius
Genius

I' m slightly unsettled about the material properties table and it pre-inserted values.

 

My impression is that the thermal conductivity for many plastics is wrong by the factor 10.

e.g.

  • Nylon: 2.1 W/(mC); .... I guess it should be ten times less i.e. about 0.25 W/(mC)  
  • Polyethylene Low Density: 4 W/(mC);...  I guess it should be ten times less i.e. about 0.4 W/(mC) 
  • PVC 1.5 W/(mC); .... I guess it should be ten times less i.e. about 0.19 W/(mC) 

Other parameters were set to zero

  • PVC specific heat 0 J/(kgK)...  I guess it should be about 850 J/(kgK)
  • Polyurethane specific heat 0 J/(kgK)...  I guess it should be about 170 J/(kgK)

 

And I feel, the use of braces might be observed from SE.

I find the units for Thermal Conductivity in SE as W/m*C, while I think it should be W/(m*K) or W/m/K, Specific Heat I find as J/kg*K instead of J/(kg*K) or J/kg/K ....

 

best regards

Hans

9 REPLIES 9

Re: Lacking reliability of the Solid Edge Material Table?

Valued Contributor
Valued Contributor

@Hans11

 

Well the materials properties can be changed according to you.

 

And if you have experimetal results that can prove your "guess" then go for it, But if you don't have the experimetal or analtical results to proove please don't.

 

Speaking about the units, I do find the type of units used by SOLID EDGE and described you in TEXTBOOKS interchangeably, so that is not a issue as such. All you need to do is to convert the units. 

Re: Lacking reliability of the Solid Edge Material Table?

Genius
Genius

@Shiv_Madan

At first I was thinking, that I was wrong. But my impression is, that some parameters are incorrect by an extent that's not covered by the vagueness of some material parameters. I want to find out, if people here agree and materials table should be checked or if my imagination of the material parameters is not correct.

 

>>"Well the materials properties can be changed according to you."<<

Yes, for shure, I can overwrite the material parameters in the built-in table. But I presume, that the values from the built-in table are often taken as a first guess and so it would be nice, if they were more or less correct. The deviation of some by one order might be just slip while typing in the values for a group of materials by the providers of the SE some time ago.

Additionally the setting of zero for some material with others set to true values will cause faulty results for simulations of assemblements, with the special disgrace that this is not recognizable on the first view, in the combination of various materials.

 

>>"All you need to do is to convert the units"<<

No I don't think so, W/m*C is mathematically unlike W/(m*C) or W/m/C.

 

best regards

Hans

 

 

Re: Lacking reliability of the Solid Edge Material Table?

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Hi @Hans11

 

 

 

I think Your request is a moer or less sopphistic one.

 

Probably 95% (even more) of us never ever have to deal with that physical property when in machine design.

This might also be the reason that till now nobody ever have seen this wrong value.

So if it is important to You, then You should adapt accroding Your requests and numbers.

 

This anyqay is something everybody should do, before working productional.

To reduce and adapt his database to show Your own specific needs.

And at the beginning only density was the one and only physical material property we had in material mtl

 

And it still was enough.

When beginning with simulation the stress values get more important and were integrated into the material data.

Expanded by those temperature properties for advanced simulations.

I do not know many people who  ever did such calculations.

To force here, such calculations and using Solid Edge.

This is not the main target of machinery CAD

 

And what belongs the units.

I only can see Solid Edge showing this units as W/m-C and J/kg-C, not W/m*C or J/kg*C

So this forme is a clear difference and again to be honest, many people are turnig off the disply of units, still this makes working easier, especially qhen working with that numbers, and entering calculations

 

regards
Wolfgang

Re: Lacking reliability of the Solid Edge Material Table?

Genius
Genius

Hi Wolfgang,

 

Thank You for clarifying this.

I'm too new in this community, so I didn't know that. If nobody ever uses the material properties table (except may be the mass) then of cause it is completely meaningless, if values are correctly set or not. I'm used to numerical FE-modeling, where material properties are important.

 

>>"W/m-C"<< looks to me like Watts divided by meter and afterwards multiplicated by degrees Celsius. I expect it should be Watt divided by meters divided by degree Celsius. But again, if nobody looks at the units, this point of mine is meaningless as well.

 

best regards

Hans

Re: Lacking reliability of the Solid Edge Material Table?

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

HI @Hans11

 

 

as said, this is a personal opionion and a personal experience.

And n, not only mass (or better to say density) is used, but also E-modul and those other stress factors which are important for structural analysis.

But again, to be honest, I suppose that not more than 10% of all Solid Edge users have a premium license, and even are able to use simulation.

As You also have said, You are coming from the numerical FE analysis side.

There total different parameters and requirements get important.

 

But also, if I'm providing a material data base, filled with values, so they should be correct, nevetheless.

 

But let me give a final "joke" (besides the fact it isn't really to laugh):

 

For many years the density for water was set with 0.0  kg/m³

But again, not to many machinery engineers are building their structures out of water.

 

 

 

regards
Wolfgang

Re: Lacking reliability of the Solid Edge Material Table?

Honored Contributor
Honored Contributor

I think the problem here is that each country has there own standard for steel formulations. So getting the material properties for each formulation would be a huge undertaking. USA, Russia, China, France, and Germany, and many more, each have it's own materials.

 

For the USA, I would at least want a few sheet metal and a few common beam formulations of steel like A36, and A992

Re: Lacking reliability of the Solid Edge Material Table?

Gears Phenom Gears Phenom
Gears Phenom

Hi Edgers,

 

Would you please explain to me what units are used for every property from the Material Table?

I cannot find the info about it within SE.

 

Density

CTE

TC

Specific Heat

Modulus of Elasticity

Poisson's Ratio

Yield Stress

Ultimate Stress

Elongation

 

Thank you,

Arek

 

Re: Lacking reliability of the Solid Edge Material Table?

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Hi @arekkul

 

 

 

those properties and their according Units are basic physical proeprties of any material.

If You are not familiar with them, I suppose that You will not need them.

Those values will be used for FE simulations tasks more than for mechanical design.

So as long as You have not to take care about stress and strength, loads and forces they will not be very important to You.

Then only the density will be Your material property which is necessary and important.

 

 

regards
Wolfgang

Re: Lacking reliability of the Solid Edge Material Table?

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Here's a screen shot on Steel. My units are set to IPS (inch). If you set it to MMKS it will display metric units. In order to display the units in the material table make sure "show units in value fields" is on on the general tab in SE options. Not sure why thermal expansion and elongation have zero for coeefficients in all materials.

MatTable.JPG

Bruce Shand
SE2019 MP8 - Insight - Win10 - K4200