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Physical properties for 3d prints

Discussion in '3D Printing' started by beastro, Sep 18, 2020.

  1. beastro

    beastro Senior Member

    Hi again,

    I am sure this must have come up before.

    Obviously there is quite a deviation from reality of the physical properties calculated by Alibre for 3d printed parts, as the partial infill is not taken into consideration. I am considering to create some dummy materials with adjusted densities to take account of that issue.
    The easiest way of course would be to have the choice of manually assigning a mass to a part that would be used for all further calculations, but of course the CG would be ill defined except for the simplest part shapes. In any case I submitted a feature request for that manual mass assignment.

    If anybody found a simple way out of this, please let me know. I am designing compound objects that include many 3d printed parts and other materials and knowing the precise CG is quite important for proper design modifications.
  2. Lew_Merrick

    Lew_Merrick Guest

    Hi Berthold -- It would seem to me that you need to Shell the "partial infill" volumes if you are to get the Mass Properties to come out correctly. Having spent no small part of 2012-3 performing "Material Properties Testing" on various "3D Printing Materials" for the USAF & NASA, I came to the conclusion that nobody in the "3D Printing Materials" market understands anything about "Materials Property Testing." -- Lew
  3. beastro

    beastro Senior Member

    Yes, I thought of that too, but apart from the substantial work and design complications in terms of the frequent bolean operations performed on those parts for fastener insets etc., still the infill would not be correctly calculated. Also, I would have to make 2 configurations for every part that have to be kept in sync, as I would need a solid "print version" and a shelled calculation version. All in all, it might be easier to get some ballpark conversion factor that conforms to a median fit for most parts..

    I will look into the Simlab composer simulation module, whether they could fill the gap.
  4. idslk

    idslk Alibre Super User

    Hello Berthold,

    have you tried do design some kind of infill by yourself so that it won't have to be done by your slicer?


    MikeHenry likes this.
  5. beastro

    beastro Senior Member

    Hi Stefan,

    That is of course an option and in some cases even a necesity to get functional infill, however in most cases, I don't think it is practical and adds unnecessary work and complexity to the task.
    Also, the newer slicer versions do such a good job of producing mechanically functional infill that it would be hard to compete with it.

    If there would be an option in Alibre to assign a shell thickness and % of infill to every part, then the proper mass could be calculated to a reasonable precision.

    Kind regards
  6. NateLiqGrav

    NateLiqGrav Alibre Super User

    If your shell/infill isn't modeled accurately it could throw off your center of gravity slightly. That being said if it's close enough just figure out your parts custom density from its volume and real life weight/mass.
  7. beastro

    beastro Senior Member

    Yes, that is what I am doing to get an aproximation.

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