Abaqus Keywords Reference Guide  
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*CORRELATION
Define cross-correlation properties for random response loading.

This option is used to define the cross-correlation as part of the definition of random loading for use in the *RANDOM RESPONSE analysis procedure. The *PSD-DEFINITION option is also needed to give the frequency function to be used with the correlation definition.

Product: Abaqus/Standard  

Type: History data

Level: Step

References:

Required parameter for TYPE=CORRELATED and TYPE=UNCORRELATED: 

PSD

Set this parameter equal to the name of the frequency function defined on the *PSD-DEFINITION option to be associated with this correlation option.

Optional parameters:

COMPLEX

Set COMPLEX=YES to include both real and imaginary terms in the cross-correlation definition. The alternative is to include real terms only using COMPLEX=NO (default).

INPUT

Set this parameter equal to the name of the alternate input file containing the data lines for this option. See “Input syntax rules,” Section 1.2.1 of the Abaqus Analysis User's Guide, for the syntax of such file names. If this parameter is omitted, it is assumed that the data follow the keyword line.

TYPE

Set TYPE=CORRELATED (default) if all terms in the correlation matrix should be included.

Set TYPE=UNCORRELATED if only diagonal terms should be used.

Set TYPE=MOVING NOISE for moving noise loading. In this case only one *CORRELATION option can be used in the step. The COMPLEX parameter cannot be used with TYPE=MOVING NOISE.

USER

Include this parameter to indicate that user subroutine UCORR will be called to obtain the scaling factors for the correlation matrix. If this parameter is included, the TYPE parameter can be set only to CORRELATED or UNCORRELATED.

Data lines for TYPE=CORRELATED or TYPE=UNCORRELATED: 

First line:

  1. Load case number defined on the loading data lines.

  2. Real part of scaling factor.

  3. Imaginary part of scaling factor. (Only needed if COMPLEX=YES.)

Repeat this data line as often as necessary to define the load cases and their associated scaling factors.

Data lines if the USER parameter is included: 

First line:

  1. Load case number defined on the loading data lines.

Repeat this data line as often as necessary to define the load cases to be correlated.

Data lines for TYPE=MOVING NOISE: 

First line:

  1. Load case number defined on the loading data lines.

  2. x-component of noise velocity.

  3. y-component of noise velocity.

  4. z-component of noise velocity.

  5. Name of the power spectral density function, defined on the *PSD-DEFINITION option, for this noise source.

Repeat this data line as often as necessary to define the random loading.