Unify energy harvesting and vibration control functions in randomly excited structures with electromagnetic devices

With the extensive studies on energy harvesting via electromagnetic devices in civil or mechanical structures, a novel dualfunction device, termed electromagnetic damping and energy harvesting (EMDEH) device, has been proposed in recent years, whose design represents a dual-objective optimization problem by considering both vibration control and energy harvesting performance. However, an argument on whether or not vibration control and energy harvesting is contradictory has arisen, based mainly on the intuition that the former tries to suppress vibration magnitude while the latter benefits from large vibration amplitude. This paper clarifies this question through a theoretical analysis of coupled structure-EMDEH systems under stochastic excitations. The closed-form solutions of the damping power, as well as the output power of the EMDEH device when attached to single-degree-of-freedom (SDOF) and multidegree-of-freedom (MDOF) structures, are given based on random vibration theory. A numerical analysis of a 20-story steel structure installed with EMDEH devices is conducted to validate the theoretical predictions. The consistency between vibration control and energy harvesting in randomly excited structures with EMDEH devices in the presence of inherent structural damping is demonstrated for the first time.