Optimum Response Structures - CAD Procedures Based on System Identification and Model Reduction

Abstract

Structural parameter identification using frequency response techniques can yield models of fairly high order. For dynamic calculation purposes such models might be conveniently reduced to lower order equivalents while the salient eigen values are retained and resonant amplitudes maintained. A computer aided procedure using well known identification and model reduction techniques is indicated where a structure has been reduced to a lower degree freedom model retaining required resonances. Complex curve fitting technique for identification of transfer function coefficients from experimental frequency response plots has been used. An iterative procedure establishes the structural parameters in mass, spring, dash pot equivalents. Standard model reduction schemes lead to reduced model, and finally, to equivalent dynamic model with all important eigen frequencies still retained in a selective manner. The procedure uses about a dozen routines excluding standard library routines.Illustrative examples of models of vertical milling machine and a multidegree freedom system are given at the end.