NOISEXYZ

I/O Options and Subcase Information Entry Defines perturbation parameters for all X1, X2, and X3 grid point coordinate values which define the location of the grid points in the model. This entry applies to the X1, X2, and X3 fields of all GRID entries in the model.

NOISEXYZ can be used to check the sensitivity of a particular model to small changes in grid point coordinates.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
NOISEXYZ MAGLMT RNDSEED

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
NOISEXYZ 1.3 1

Definitions

Field Contents SI Unit Example
MAGLMT Defines the Magnitude Limits of Perturbation for all grid points. This is a maximum real number value by which the current grid point coordinates can be increased or decreased. Each coordinate of each GRID is modified by adding an independent random value in the range [-MAGLMT, +MAGLMT].

No default (Real > 0)
RNDSEED Defines the seed for random process computing perturbation values, when reproducibility of results is required. With RNDSEED=0 (or blank) every time OptiStruct runs, the perturbation will be different (chosen within the interval (-MAGLMT, +MAGLMT)), but when any non-zero value is used for RNDSEED, then consecutive runs with the same value for RNDSEED will produce identical perturbations.

Default = 0 (Integer ≥ 0)

Comments

  1. The ECHO I/O Options Entry can be used in conjunction with NOISEXYZ to print the perturbed grid point coordinates to the .out file.
  2. NOISEXYZ is applied prior to the processing of the CONNECT Bulk Data Entry (if present), which will likely affect the connectivity of parts.
  3. The following is a perturbation example of a Grid Point Coordinate:
    INPUT
    GRID,1,0,0.0,0.0,0.0,0
GRID,2,0,10.0,0.0,0.0,0
NOISEXYZ,0.2
    ECHO
    GRID,1,0,6.22070312-2,-6.6479492-2,4.11560059-2,0
GRID,2,0,9.8447753906,-.1767333984,-.188873291,0