May, James E. 2009. Nonlinear vibration control of long flexible structures employing intermodal energy transfer (modal damping). PhD Thesis. University of Akron. 314 pp.
From the introduction
In the not too distant past, the design philosophy for tall civil structures could be summarized as LARGE MASS-LARGE STIFFNESS. The information age has brought about advances in material science and design technologies that provide the means to explore and construct high-reaching, expansive and much lighter-duty geometries. Current design trends require not only extensive strength-based engineering, but also carefully executed motion-based analysis. Tall, flexible civil structures have long been known to be prone to low frequency transverse vibrations. To further complicate matters, the associated natural damping properties are small leading to drawn out settling times. Motion-based augmentations offer enabling solutions. This research develops, evaluates and demonstrates a modal-based motion control strategy that may be viable for a select grouping of flexible structures. ‘Modal Damping’ exploits damping mechanisms inherent in structures by capitalizing on distinctive dynamic properties existing among the structures vibration modes. An automated, non-linear control scheme was developed to transfer energy from the fundamental vibration mode, where most vibration energy of the civil structures of interest resides, to higher order modes where vibration impedance was shown to be more effective. To achieve this objective, Modal Damping employs motion control forces self-powered by the redistribution of fundamental mode kinetic energy making the strategy highly efficient. The Modal Damping concept was developed and analyzed via dynamic simulation. The analytical findings were then applied to design an experimental model that was constructed and utilized to conduct a concept demonstration and evaluation
This paper has great overview of damping issues, structures, and history, along with good model building an analysis.
Keywords: damping, viscous, node, nodal, vibration, tuned mass damper, modal damping flexible structure, energy transfer
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