Substructure system identification and synthesis

Abstract

This paper explores the possibility of performing system identification at the substructure level and then synthesizing the results to obtain 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 parameters are presented. Some potential testing difficulties and possible solution approaches are also discussed. A mass-loaded interface approach 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.