Material properties units Simlab

RokHodnik
RokHodnik Altair Community Member
edited October 2020 in Community Q&A

Hello!

One quick question.

 

When inputing units into materials manager in Simlab I often have problem with knowing in what units to input the property data.

 

For example is the unit for Density kg/m^3 or g/mm^3 or kg/dm^3 or kg/mm^3?

image.png.fccdc4d80016236a28645d217343308b.png

 

In tutorials people are usualy inputing data in XX units for example for steel 7.8e-9 units.

 

Steel has:

7650 kg/m^3

0.00765 g/mm^3

7.65 kg/dm^3

7.65 e-6  kg/mm^3

 

So what is the input unit?? I think it is kg/mm^3 but then tutorials input false data.

 

Specific density SI unit is kg/m^3.

 

Below is example from tutorial.

image.png.b8f640631a6741d87f90a08612c832e6.png

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Answers

  • RokHodnik
    RokHodnik Altair Community Member
    edited June 2019

    Calculating Mass property confirms the 7.65e-6  kg/mm^3. Please confirm my statement.

    The modeled structure sholud have cca. 200g of mass.

     

    Input density in this case is 7.65e-6  kg/mm^3.

     

    Still confused with tutorial input data and default input data in the box. As 7.8e-9 density is not used for any material why should it be default value...

    image.png.f43a3e2582a869122a42ebdb3ea891aa.png

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited June 2019

    7.89 e-9 for density is tonnes/mm3.So mass will be tonnes. Simlab is unit less,So please ensure unit consistency in the model.

  • RokHodnik
    RokHodnik Altair Community Member
    edited June 2019

    Thx for help @Rahul R.

    I think Altair should consider adding unit labels next to the input boxes.

    If there is no unit label user would expect SI units so you can easily get confused with critical parameters.

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited June 2019

    HyperMesh 2019 does allow option of setting CAD import/export with target unit system.I believe Simlab too will have unit system support in near future. 

    <?xml version="1.0" encoding="UTF-8"?>Unit system.png

  • RokHodnik
    RokHodnik Altair Community Member
    edited June 2019

    @Rahul R yes it would be convenient.

     

    Still waiting on your reply on my other topic of acoustic analysis :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' /> ...

  • Kamalraj
    Kamalraj
    Altair Employee
    edited June 2019

    Hi, Unit system support in SimLab currently in under development. Hopefully it will be supported end of this year. 

  • AlessioLibrandi
    AlessioLibrandi
    Altair Employee
    edited June 2019

    Dear Rok,

     

    Altair SimLab does not have yet explicited units of measure, but this enhancement will happen very likely in the next release (SL 2019.2). 
    Until then, please consider to adopt always consistent system of units. You can follow the guidelines I attach here.

     

    Thank you

     

    Unable to find an attachment - read this blog

  • RokHodnik
    RokHodnik Altair Community Member
    edited June 2019

    Dear Rok,

     

    Altair SimLab does not have yet explicited units of measure, but this enhancement will happen very likely in the next release (SL 2019.2). 
    Until then, please consider to adopt always consistent system of units. You can follow the guidelines I attach here.

     

    Thank you

     

     

    Attatchment unavailable.

    Unable to find an attachment - read this blog

  • AlessioLibrandi
    AlessioLibrandi
    Altair Employee
    edited July 2019
  • RokHodnik
    RokHodnik Altair Community Member
    edited July 2019

    Still no success.

     

    image.png.21df3b6f73249d2992051dc1cfc8024b.png

    image.png.30824b54ab5f81b0aefc756a99614f25.png

  • Rahul_P1
    Rahul_P1
    Altair Employee
    edited July 2019

    HI, we apologize for the inconvenience , you should be able to download the file now, please let us know if there are further concerns,

    Unable to find an attachment - read this blog

  • RokHodnik
    RokHodnik Altair Community Member
    edited July 2019

    @Rahul Ponginan thank you. 

    So if I understand correctly when observing acceleration of a point of a structure it is in unit mm/s2?

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