Very Flexible Aircraft Damping Characterization and the Support System Impact During Ground Vibration Testing

This paper presents the investigation of various damping models and modeling techniques for very flexible structures, with the goal of identifying approaches that best reflect the damping measured during ground vibration testing in the presence of a support. Both computational and experimental methods are employed to characterize and isolate damping contributions from structural and non-structural sources, such as suspension systems. The finite element model of the test articles is modified to incorporate different damping representations and deformation-dependent effects, with the goal of obtaining a more realistic prediction of modal behavior. Experimental damping data obtained during ground vibration testing are used to validate these models and examine whether and how damping changes with structural configuration and loading state. The results indicate that the damping changes with the damping model, the structural configuration, the loading state, and whether the very flexible test case is an isotropic, simple structure or a complex built-up structure.