NEW MODAL SYNTHESIS TECHNIQUE USING MIXED-MODES

A new modal synthesis technique using mired modes is introduced. The m ethod not only has a simple form, high precision, and efficiency, but it also provides two reliable criteria for determining the truncation frequency of system synthesis modes, These have been demonstrated in d etail by the numerical examples. The key point of the method is as fol lows. The exact residual modes containing the effects of higher-order, free-interface modes are expressed analytically in terms of some lowe r-order, fixed-interface modes, and then the substructural displacemen ts are expressed accurately in terms of some lower-order, mixed modes, i.e., the linear combinations of the lower-order fixed-interface mode s and lower-order, free-interface modes, instead of the assumed substr uctural displacements employed in general modal synthesis, so that onl y linear synthesis equations are involved in this new method, although the contributions of all higher-order modes are included.