Newton unit dimension - MotionView 2022.1

Thomas_Bécue
Thomas_Bécue Altair Community Member
edited January 24 in Community Q&A

Hello,
I have troubles with MV units.
Curently, here are my solver units :

In my MV model, I want to apply a torque, using a Spring Damper object.

The units for the torque properties seems to be : N.mm.s/rad. Am I right for this ?

Also, the dimension definition of the N in SI is : kg.m/s².
But in MV, is N become kg.mm/s² ?
If yes 1 N/m become 10^6 N/mm in MV.

Does someone have a clue about this?

Thanks in advance.
Thomas

Best Answer

  • Vishvam
    Vishvam
    Altair Employee
    Answer ✓

    Hello @Thomas_Bécue
    You are right in understanding the units for spring damper. I am assuming you meant units for the damping property to be (N-mm-s/rad). This is correct.

    Regarding the second question about SI unit of force being kg-m/s², it should be noted that force is a function of the first three and can be automatically calculated for a consistent set of units. So we always give force units (N) in SI for all the entities in Motionview. The dependent conversions are taken care in the backend by the solver. Here is detailed documentation on units.

    Hope this answers your query!

Answers

  • Vishvam
    Vishvam
    Altair Employee
    Answer ✓

    Hello @Thomas_Bécue
    You are right in understanding the units for spring damper. I am assuming you meant units for the damping property to be (N-mm-s/rad). This is correct.

    Regarding the second question about SI unit of force being kg-m/s², it should be noted that force is a function of the first three and can be automatically calculated for a consistent set of units. So we always give force units (N) in SI for all the entities in Motionview. The dependent conversions are taken care in the backend by the solver. Here is detailed documentation on units.

    Hope this answers your query!

  • Thomas_Bécue
    Thomas_Bécue Altair Community Member

    Hi,
    Okay perfect, thanks!

    Have a good day sir

  • Thomas_Bécue
    Thomas_Bécue Altair Community Member
    edited January 24

    @Vishvam
    I have another question.
    Is there an object more adapted to applied a rotational torque (N.mm) in a system than a SpringDamper ?
    SpringDamper looks more useful to add angular stiffness? I was using it by putting Stiffness to 1 N.mm/rad and Preload Torque to great value. In order to apply only a constant rotational torque.

    Maybe with rotationnal force ?

    Thanks in advance,
    Thomas

  • Orestis_YB
    Orestis_YB
    Altair Employee

    Hello @Thomas_Bécue,

    you are right! Rotational force is the way to go. You can access it from the microdialog when selecting the force tool

    You can apply the torque as action only or action reaction between two bodies. You can find more information in the documentation. If you are new to Multibody modeling I would strongly suggest to go through our MotionView/MotionSolve Introduction v2023 eLearning. Hope this helps!

    Best regards,
    Orestes

  • Thomas_Bécue
    Thomas_Bécue Altair Community Member

    Hi!
    Okay perfect !

    Thanks, have a good day.

    Thomas