TAMeig


Purpose

Calculates modes based on the TAM matrices.

Syntax

SA = TAMeig(TAM[,'allmodes'])

Description

TAMEIG calculates modes based on the TAM matrices with less than critical damping and positive imaginary roots.

TAM is a tam structure, such as that returned from load_tam. The minimum required fields are TAM.mass, TAM.stiffness, and TAM.aset. In this case, normal modes are returned based on eig(TAM.stiffness,TAM.mass). If TAM.hysteretic is also supplied, complex modes are returned based on eig(TAM.stiffness+sqrt(-1)*TAM.hysteretic,TAM.mass). If TAM.viscous is supplied as well, complex modes are returned based on state space formulation eig(A,B), where:

A= [C K;K 0], B=[M 0;0 -K], where

M = TAM.mass
C = TAM.viscous
K = TAM.stiffness + TAM.hysteretic*sqrt(-1)

'allmodes' returns all calculated modes, including those with negative imaginary roots and greater than critical damping.

TAMEIG attempts to handle a TAM with SPOINTs. SPOINTs show up in the DOF list as a node with no direction. If SPOINTs are found, and their IDs do not conflict with any node IDs, their shape coefficients will show up as having an X direction. If their IDs do conflict, TAMEIG will issue an error.

SA is an imat_shp object containing modes. Negative natural frequency implies negative imaginary roots.

Examples

>> sa=TAMeig(TAM);

See Also

load_tam, eig