Passive vibration energy management through intentional nonlinearity

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In essence, nonlinearity is a dynamical mechanism for scattering vibration energy across temporal or spatial scales (e.g., frequencies / wavenumbers, or system modes). Moreover, nonlinear effects are highly tunable with (or passively adaptive to) energy and other system parameters, a feature which enables new and unprecedented passive multi-functionality in engineering systems. This contrasts to linear systems where no such passive effects can be induced given their lack of capacity for multi-frequency harmonic generation. Engineering nonlinearity, therefore, has become an interesting and potentially transformative emerging trend, with great promise for the future. In this talk we present our vision regarding this exciting new field, by overviewing some basic elements of nonlinear energy management in vibration engineering. This includes, capacity for targeted energy transfers (TET) to nonlinear energy sinks; intermodal TET in structural systems, and interband TET in phononic systems; energy redirection in preferential directions; affecting and tuning the nonlinear bandwidth of nonlinear oscillators through multi-harmonic energy scattering; enhanced vibration and shock isolation; nonlinear vibration energy harvesting; rapid and effective inherent dissipation, and other effects. Predictively and reliably engineering nonlinear effects for energy management dictates a comprehensive physics-based understanding of multi-scale complex processes and phenomena, accompanied with powerful computational tools and rigorous experimental validation. Hence, the discussed nonlinear concepts and methods need to be closely tied to physical insight and progress in modern computational techniques such as machine learning. Moreover, unwanted nonlinear effects such as instabilities, uncontrollable chaotic responses or unwanted co-existing dynamics, just to name a few, need to be avoided by careful predictive design. Through two examples we demonstrate the efficacy of engineering nonlinearity in oscillating systems to induce new, heretofore unavailable features in dynamical systems in predictable and controllable ways.