Modal Analysis of a Flexible Three-Link System in Variable Configurations

In this paper, some experimental results of modal tests performed on a large three-link flexible system are reported. These modal tests were conducted at the NASA’s LSS GTF (Large Space Structures Ground Test Facility) located at MSFC (Marshall Space Flight Center). The experimental results were obtained for various configurations and compared with those obtained using the Component Mode Synthesis technique. The mode functions were selected to keep the computation as simple as possible without compromising the accuracy. The results obtained from the dynamic software simulation package called TREETOPS have also been included for completeness. It is found that the experimental results are in excellent agreement with those obtained by the use of component mode techniques for the aforementioned structures. The average percent change in the frequencies is observed to be 6.09%, while the average mode shape correspondence is noted as 94.5%.