3 Replies Latest reply on Jul 22, 2014 11:44 PM by Jared Conway

    Remote Mass Moments of Inertia?

    Mark Egan

      Can anyone explain to me what the mass moments of inertia settings within the Remote Mass simulation feature do? Is a lumped mass not a point mass by definition? How is ascribing a moment of inertia to it useful? Does this moment of inertia setting affect the properties of the rigid bars to which they attach?

        • Re: Remote Mass Moments of Inertia?
          Shaun Densberger

          A lumped mass is a point mass by definition, meaning that it doesn't have rotational moments of inertia. Any rotational inertia effects (provided that ones haven't been defined in the dialog box you highlighted) will come about from the connection between the elements and mass point via the rigid bars. However, this might not capture all of the rotational inertia effects. For example, if the model were to rotate about the mass point, then the only rotational inertia effects would be due to the elements on the outer structure. If you were to define the inertia matrix for the mass point, then you'd also have those values contribute.

           

          The properties of the rigid bar elements are unaffected. You can think of a rigid bar as an enforcement of nodal compatibility (i.e. the relative motion between the two ends of the bar must remain constant). Keep in mind that the effect of this is that your model is typically stiffer that it would normally be; whether or not this is an issue depends on the specifics of the model.