PARAM, GRDPNT

Bulk Data Entry Obsolete Nastran parameter that will give information about the mass properties of the structure.

Parameter Values Description
GRDPNT <GID>

Integer ≥ -1

 Activates output of Grid Point Weight properties like center of gravity and moment of inertia. This parameter does not affect output of OUTPUT,MASSPROP. It also does not affect how mass properties are calculated within either analysis or optimization solutions. This parameter is primarily to generate output related to grid point weight properties to the .out file and does not affect the results of the solution.
Accepts either single integer input (GID) or multiple real values (X,Y,Z).
-1 (Default)
No output from grid point weight generator.
0
The center of gravity coordinates are relative to the origin of the basic coordinate system and are expressed in the coordinate system CID.
> 0
The center of gravity coordinates are relative to GID and are expressed in the coordinate system CID.
<X,Y,Z>

Real

No default

 The center of gravity coordinates are relative to <X,Y,Z> and expressed in the coordinate system CID.

Comments

  1. The coordinate system CID is defined by PARAM, UCORD.
  2. If PARAM, UCORD is not specified, CID = -1, or CID given is not found, all values are calculated relative to the basic coordinate system.
  3. If PARAM, GRDPNT is not specified in the input deck, then the corresponding printing of center of gravity and moment of inertia are not output in the .out file regardless of the value of PARAM, UCORD.

    If OUTPUT,MASSPROP is defined, the output of center of gravity and moment of inertia is available, regardless of PARAM,GRDPNT.

  4. The values of PARAM, GRDPNT does not affect the output of Center of Gravity and Mass Moment of Inertia output in OUTPUT, MASSPROP.

    OUTPUT,MASSPROP related printing is in a different section of the .out file (compared to GRDPNT). Additionally, OUTPUT,MASSPROP printing is repeated for each optimization iteration (only once for analysis run). Whereas, PARAM,GRDPNT related output is only printed once at the beginning of the .out file.

  5. If GID > 0, but the grid point is not found in the model, the center of gravity coordinates are relative to the origin of CID defined by PARAM, UCORD.
  6. If the mass property is coupled due to inconsistent scalar mass, a Warning (No. 5606) with the corresponding coupling ratio will be printed to the .out file. In such situations, the output is provided in the principal directions.
  7. Output with this PARAM is calculated based on mass matrix and in mesh dependent. On the other hand, the inertia calculated in optimization or OUTPUT,MASSPROP is done with proper integration for each element.
  8. CMASS1 and CMASS2 elements can be excluded from Grid Point Weight Generation using PARAM,GRDPNTCM,NO.