Mapdl.cmsopt(cmsmeth='', nmode='', freqb='', freqe='', fbddef='', fbdval='', iokey='', **kwargs)

Specifies component mode synthesis (CMS) analysis options.



The component mode synthesis method to use. This value is required.

FIX - Fixed-interface method.

FREE - Free-interface method.

RFFB - Residual-flexible free-interface method.


The number of normal modes extracted and used in the superelement generation. This value is required; the minimum is 1.


Beginning, or lower end, of frequency range of interest. This value is optional.


Ending, or upper end, of frequency range of interest. This value is optional.


In a free-interface (CMSMETH = FREE) or residual-flexible free- interface (CMSMETH = RFFB) CMS analysis, the method to use for defining free body modes:

FNUM - The number (FDBVAL) of rigid body modes in the calculation.

FTOL - Employ a specified tolerance (FDBVAL) to determine rigid body modes in the


FAUTO - Automatically determine rigid body modes in the calculation. This method is the


RIGID - If no rigid body modes exist, define your own via the RIGID command.


In a free-interface CMS analysis (CMSMETH = FREE), the number of rigid body modes if FBDDEF = fnum (where the value is an integer from 0 through 6), or the tolerance to employ if FBDDEF = ftol (where the value is a positive real number representing rad/sec). This value is required only when FBDDEF = fnum or FBDDEF = ftol; otherwise, any specified value is ignored.


Output key to control writing of the transformation matrix to the .TCMS file (FIX or FREE methods) or body properties to the .EXB file (FIX method).

TCMS - Write the transformation matrix of the nodal component defined by the OUTPR

command to a .TCMS file. Refer to TCMS File Format in the Programmer’s Reference for more information on the this file.

EXB - Write a body property input file (.EXB file) containing the condensed

substructure matrices and other body properties for use with AVL EXCITE. Refer to ANSYS Interface to AVL EXCITE in the Substructuring Analysis Guide for more information.


CMS employs the Block Lanczos eigensolution method in the generation pass.

CMS supports damping matrix reduction when a damping matrix exists. Set the matrix generation key to 3 (SEOPT,Sename,SEMATR) to generate and then reduce stiffness, mass, and damping matrices.

CMS does not support the SEOPT,,,,,RESOLVE command. Instead, ANSYS sets the expansion method for the expansion pass (EXPMTH) to BACKSUB.

For more information about performing a CMS analysis, see Component Mode Synthesis in the Substructuring Analysis Guide.

If IOKEY = TCMS is used to output the transformation matrix, then only ITEM = NSOL is valid in the OUTPR command. In the interactive sessions, the transformation matrix will not be output if the model has more than 10 elements.

This command is also valid in /PREP7.