hm_getmoiofsolid

Calculate and return the 3 moment of inertia (Ixx, Iyy, Izz) and 3 product of inertia (Ixy/Iyx, Iyz/Izy, Ixz/Izx) values (MOI) for a single solid geometric entity.

Syntax

hm_getmoiofsolid solid_id ?density?

Type

HyperMesh Tcl Query

Description

This command will return 6 values defining the moment and product of inertia values from the specified solid entity:

Ixx Iyy Izz Ixy Iyz Izx

These values will be calculated relative to the center of gravity/center of mass of the solid (obtained using hm_getcentroidofsolids) and the global coordinate system “translated” to the COG. The user will specify the density value to use for the calculations.

If a density is not given, then the returned values are the “mass normalized” values, where the MOI values are reported normalized by value of volume*1.0. The volume can be calculated using hm_getvolumeofsolid.

Inputs

solid_id: The ID of the solid.
density (optional): Density value of the solid. If specified, must be > 0.

Examples

To get the "true" MOI for a solid with ID 10 and a density of 1e-9:

hm_getmoiofsolid 10
            0.000000009

To get the "mass normalized" MOI for the solid with ID 10:

hm_getmoiofsolid 10

Errors

Incorrect usage results in a Tcl error. To detect errors, you can use the catch command:

if { [ catch {command_name...} ] } {
   # Handle error
}

Version History

10.0