Dissipation induced by substructures and distribution of vibratory energy in a complex system

This work is concerned with the problem of energy transfer that takes place between a master structure and the substructures attached to it. The response of the system is characterized by the impedance of the substructures and it determines whether the induced damping is real or apparent. When the dissipation is real the master structure has a larger loss factor than that of the substructures and there will be continuous transfer of vibratory energy from the master structure to substructures. However, in the case of apparent damping, one can observe that the vibration energy is transferred back and forth between the master and substructures. Some combinations of the master and substructures have been considered to examine this phenomenon and to determine the criteria for damping. It has found that a modal overlapping condition, which corresponds to bandwidths that exceed the spacing of those natural frequencies, is crucial in determining the characteristics of the system damping. The result of this paper is consistent with that found with the fuzzy structure and SEA framework. [Work sponsored by Ministry of Education, Korean Government under the BK21 program and Ministry of Science and Tech., Korean Government under National Research Lab. program.]