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G. Composite Damping

Composite modal damping is based on a weighted average of strain energies in each material, (or element), for each mode (eigenvector).

The critical composite damping term DJ for mode J is computed by:

D i = Σ i = 1 n { ϕ i } T b i [ k ] { ϕ i } { ϕ j } T [ K ] { ϕ j }
total number of degrees of freedom
equivalent percent of critical damping associated with component i
mode shape vector for mode J
stiffness associated with component i
stiffness matrix for the system