PHYSICAL INTERPRETATION AND APPLICATION OF A COMPONENT MODAL SYNTHESIS TECHNIQUE (MODAL FORCE METHOD)

摘要

A direct substructure modal synthesis technique named modal force method for determining the dynamic characteristics of a structure is developed. The modal force method works directly with the substructure frequency response function (FRF) matrices, while the impedance method requires the inversion of these matrices. This is the key difference which makes the modal force method efficient. The method is further applied to system dynamic modification. The algorithm for the system modification can be utilized to shift any system eigen frequency to a desired value, and the corresponding eignevector is obtained at the same time without additional calculation. It delineates the possibility of shifting the eigen frequency by modifying a selected system parameter. The physical interpretations of the modal force and the FRF for modification are discussed.