$ FILE RFLAGrdm.txt  
October 22, 1999
Revised October 25, 1999

A DMAP ALTER PACKAGE FOR ENFORCED MOTION IN FREQUENCY REPSONSE ANALYSIS, rflaga.v707 

This alter package provides an enforced motion capability for sol 108. 

EXECUTIVE INPUT FILE 

Add INCLUDE 'rflaga.v707' before the CEND command. 

CASE CONTROL INPUT FILE 

The forces required to provide enforced motion may be output by the SPCFORCE command.  Enforced motion input is selected by the DLOAD command

BULK DATA INPUT FILE 

1.  Enforced Motion 

The DOFs used for enforced motion are listed on USETi entries.  

$USET,  BE,     GID1,   C,      GID2,   C2, . . .
USET,   BE,     11      123

The be-set is used for enforced motion DOFs. 

If enforced velocity and/or enforced acceleration is desired the DMIG,DVA entry is required.  Any DOFs listed here must also be listed on USET, BE entries.

$               0       IFO     TIN     TOUT                    NCOL
DMIG,   DVA,    0,      9,      1,      0,      ,       ,       1 $ HEADER
$DMIG,  DVA,    1,      0,      ,       GID,    C,      A1
DMIG,   DVA,    1,      0,      ,       11,     1,      1.0 $ DISPL. INPUT 
DMIG,   DVA,    1,      0,      ,       11,     2,      2.0 $ VELOCITY INPUT 
DMIG,   DVA,    1,      0,      ,       11,     3,      3.0 $ ACCEL. INPUT 

When enforced displacement only is input the DMIG, DVA entry is not required. When enforced velocity and/or enforced acceleration are mixed with enforced displacement all enforced motion variables must be listed on the DMIG, DVA entry.  In the example above a column vector is used to input this data (NCOL=1 in the header).  Grid point 11, component 1 is used for enforced displacement (A1=1.0).  Grid point 11, component 2 is used for enforced velocity (A1=2.0), and component 3 is used for acceleration (A1=3.0). 

Dynamic enforced motion is input on the same type of input entries used for applied loads except that the functions applied describe displacement, velocity, or acceleration rather than loads.  

DEMONSTRATION PROBLEMS:

See rflagaxy.dat in the same directory as this note, where 'x' symbolizes 08, the code for sol 108 test problems, and 'y' symbolizes a two digit number used to identify problems.  The following problems are provided in the intitial release of this capability.

rflag0810.dat	Small verification-type problem, direct analysis
rflag0811.dat	Same problem solved with CMS.

KNOWN ERRORS:

1. The LMT technique used for enforced motion presently causes large ratio warning messages of the type 

*** USER INFORMATION MESSAGE 4158 (DFMSA)
 ---- STATISTICS FOR SPARSE DECOMPOSITION OF DATA BLOCK SCRATCH  FOLLOW
        NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL =      0
        MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL =  4.9E+15 AT ROW NUMBER         12


to appear.  These messages are spurious, and may be safely ignored.  

Errors fixed in the 25 Oct revision are listed in comments at the top of the alter package.