Modal test structure project status report

The objectives of the study were to develop a simple test structure which could be used to compare modal systems and modal methods. A secondary objective would be to develop a structure which could be used to train newcomers to modal testing. We wanted a structure which would be easy to analyze, have well defined properties, be easy to fabricate, and have both widely spaced and closely coupled modes. The widely spaced modes could test the single degree of freedom methods and the closely coupled modes could test the multiple degree of freedom methods. Most test structures have very low damping, while most real structures have significant damping. Each range of damping presents its own problems for modal extraction. We wanted to find a mateial with a moderate amount of damping to more closely model the kinds of structures frequently tested.