Selection of tested component to predict dynamic properties of large structures by component modal tests

Abstract

Large flexible structures cause the full-scale ground tests to be impossible sometimes because they are not strong enough to withstand the force of gravity. The focus of the research into this problem is to confirm the dynamic characteristics of large structures without testing the whole structure. Admire et al. used the mass additive method in a modal test to avoid problems associated with design and development of test fixtures for Space Shuttle payloads [1]. Karpel et al. proposed a method to test components with boundary coordinates loaded with rigid, heavy dummy masses supported by soft springs [2]. Dummy masses generate local displacements near the boundaries to predict the dynamic properties of the whole structure. Misawa and Funamoto [3] proposed a method to predict the dynamic characteristics of large structures with component modal tests. In this method, to simulate the dynamic behavior of structures, reduced mass and stiffness matrices of untested components are replaced with a mass and a spring attached to a tested component. Misawa et al. showed a procedure to select a location with additional mass and stiffness for measuring accurate dynamic characteristics of structures by component modal tests [4]. This method needs no CMS.