*MATRIX ASSEMBLE

Keyword type: model definition

This keyword card is used to define a substructure (sometimes called a superelement in other codes), cf. Section 6.2.48. There are two required parameters NAME and STIFFNESS FILE and one optional parameter MASS FILE.

The name of a substructure consists of at most 4 characters. Internally, a “U” is appended in front of them and the substructure is considered as a special kind of user element. Therefore, the name of a substructure should not coincide with the characters following “U” of any coded user elements (such as S3 for the US3 element).

The STIFFNESS FILE refers to the file containing the entries in the stiffness matrix. It is assumed to be symmetric and only the upper triangular values or the lower triangular values should be contained (including the diagonal) in the form

  row node,row dof,column node,column dof,value

one entry per line. The order is irrelevant. The same applies to the mass matrix. The latter is only needed in frequency (*FREQUENCY) or dynamic (*DYNAMIC) calculations. The name of the stiffness and the mass matrix can be at most 80 characters long.

First line:

• *MATRIX ASSEMBLE
• Enter any parameters and their value

Example:

*MATRIX ASSEMBLE,NAME=TEST,STIFFNESSFILE=beampsuper.stiff

defines a substructure with name TEST. The stiffness matrix is stored in file “beampsuper.stiff”.

Example files: beamfsuper,beampsuper, segmentsuper.