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External Matrix

In some instances a stiffness matrix may have been determined outside GSA. This can then be included directly onto the structure matrices during the analysis

Definition​

Node and Direction

A node and direction identifies a degree of freedom (row or column in the structure matrices), so this identifies the stiffness and mass to associate with a particular degree of freedom.

Stiffness and Mass

The is the stiffness and mass associated with the defined degree of freedom. If only static analysis is required then the mass terms can be ignored.

Note​

The terms defined for stiffness and mass should not lead to non-positive definite matrices.