Command Default

Do not use any automatically generated MDOF.

Notes

Specifies automatic master degree of freedom (MDOF) generation. The limit on the number of MDOF is equal to the maximum in-memory wavefront size (see the Basic Analysis Guide). If NS is defined as the number of master degrees of freedom specified with the M or MGEN command, NTOT-NS additional master degrees of freedom will be automatically generated during the solution phase if TOTAL is used. NS may be zero, i.e., all master degrees or freedom can be automatically generated. After the solution phase, generated masters become specified masters (NS = NTOT) so that they may be listed, displayed, modified, etc. The TOTAL command is ignored in subsequent solutions unless masters are deleted, such that NS<NTOT. If used in SOLUTION, this command is valid only within the first load step.

During the matrix triangulation (wavefront) operation, the first NTOT degrees of freedom are temporarily identified as masters and then are replaced as degrees of freedom with lower K/M ratios are found. Degrees of freedom matching the user specified set (if any) are permanently identified. The wavefront builds to NTOT and will have a minimum (and final) value of NTOT. The final set of automatic masters identified will be those corresponding to the lowest modes of the structure.

Constrained degrees of freedom are excluded from the automatic master selection. Constraints may be defined to prevent undesirable modes from being present (thus preventing the corresponding MDOF from being selected). For example, if symmetry constraints are imposed, degrees of freedom producing only symmetric modes will be selected. In-plane rotational degrees of freedom for shell elements lying in a global plane are automatically excluded. All rotational degrees of freedom can be excluded during the automatic selection if desired.

If automatic master selection is used in the reduced linear transient dynamic (ANTYPE,TRANS) analysis or the reduced harmonic response (ANTYPE,HARMIC) analysis, be sure to force the selection [M] of any degrees of freedom having nonzero displacement or force inputs. If automatic master selection is used in the superelement generation pass (ANTYPE,SUBSTR), be sure to force the selection of connection points to nonsuperelements.

Automatically selected masters are shown in the solution listing (and not in preprocessing listings) as follows:

In the substructure generation pass (ANTYPE,SUBSTR), a mass matrix must be available if the TOTAL option is to be used.

If you select the sparse solver as the equation solver, any TOTAL commands are ignored. The TOTAL command is only valid for the frontal solver.

We recommend that you define as many MDOF as you can based on your knowledge of the dynamic characteristics of the structure and let the program choose a few additional masters with the TOTAL command.

This command is also valid in PREP7.

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