Mapdl.m(node='', lab1='', nend='', ninc='', lab2='', lab3='', lab4='', lab5='', lab6='', **kwargs)

Defines master degrees of freedom for superelement generation analyses.

APDL Command: M


Node number at which master degree of freedom is defined. If ALL, define master degrees of freedom at all selected nodes (NSEL). If NODE = P, graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI). A component name may also be substituted for NODE.


Valid degree of freedom label. If ALL, use all appropriate labels. Structural labels: UX, UY, or UZ (displacements); ROTX, ROTY, or ROTZ (rotations). Thermal labels: TEMP, TBOT, TE2, TE3, …, TTOP (temperature). Electric labels: VOLT (voltage).

nend, ninc

Define all nodes from NODE to NEND (defaults to NODE) in steps of NINC (defaults to 1) as master degrees of freedom in the specified direction.

lab2, lab3, lab4, … , lab6

Additional master degree of freedom labels. The nodes defined are associated with each label specified.


Defines master degrees of freedom (MDOF) for superelement generation. If defined for other analyses, MDOF are ignored. If used in SOLUTION, this command is valid only within the first load step.

Repeat M command for additional master degrees of freedom. The limit for the number of master nodes used is determined by the maximum system memory available.

The substructure (ANTYPE,SUBSTR) analysis utilizes the matrix condensation technique to reduce the structure matrices to those characterized by a set of master degrees of freedom.

Master degrees of freedom are identified by a list of nodes and their nodal directions. The actual degree of freedom directions available for a particular node depends upon the degrees of freedom associated with element types (ET) at that node. There must be some mass (or stress stiffening in the case of the buckling analysis) associated with each master degree of freedom (except for the VOLT label). The mass may be due either to the distributed mass of the element or due to discrete lumped masses at the node. If a master degree of freedom is specified at a constrained point, it is ignored. If a master degree of freedom is specified at a coupled node, it should be specified at the prime node of the coupled set.

Substructure analysis connection points must be defined as master degrees of freedom.

This command is also valid in PREP7.