Component Modal Tests with Additional Mass and Stiffness

Abstract

This paper describes a method to predict the dynamic characteristics of large structures, such as satellite antennas and solar paddles. It has become increasingly difficult to perform modal tests for large space structures, because they are not strong enough to withstand the force of gravity. Component modal tests are effective at identifying the dynamic characteristics of structures consisting of several components. In this method, the effect of untested components are considered as additional mass and stiffness attached to a tested component. Additional mass and stiffness, attached to an arbitrary coordinate, are found by reducing mass and stiffness matrices of untested components. Modal tests for different tested components give identical frequencies, so these frequencies are considered the frequencies of structures. The feature of the proposed method is to obtain the dynamic characteristics of large structures with component modal tests and to need no component mode synthesis. Numerical examples show that the proposed method has the potential to predict the dynamic characteristics of large structures by component modal tests.