This paper explores the possibility of performing system identificatio
n at the substructure level and then synthesizing the results to obtai
n an analysis model for the assembled structure. The study here shows
that to produce exact substructure coupling, the input-output transfer
function relations among all of the interface degrees of freedom must
be measured. Procedures for assembling substructure transfer function
data, substructure state-space models, and substructure Markov parame
ters are presented. Some potential testing difficulties and possible s
olution approaches are also discussed. A mass-loaded interface approac
h is proposed to produce interface excitations without using actuators
. A spring-supported boundary approach is developed for the testing of
free substructures. Some feasible testing setups for the measurement
and excitation of the interface rotational degrees of freedom are also
included. The proposed methods are illustrated by a numerical example
.