An analytical model of a piezoelectric energy harvesting device integrated with a rotational vibration absorber

In recent years the interest in energy harvesting has increased and most of the work done has been driven by the need to supply sensors for condition monitoring. Several power sources are directly available in the environment where sensors operate. In particular, the mechanical vibration of the host structure is a potential source for energy harvesting devices and the idea to convert mechanical to electric energy is very attractive. A wide range of methods and techniques have already been developed and proposed for this purpose but most of the work carried out so far, refers to transversal vibrations. Nevertheless, because rotation is a widely used form of power transmission, this work restricts its attention to rotational vibrations, with reference to a specific system of a drive-train. Rotational vibrations often affect the normal operation of these mechanical systems and the use of absorbers to reduce the vibration of the primary structure is very common. On the other hand, rotational vibration absorbers have potential for energy harvesting capabilities and only a few studies are available about this topic. However, coupling structural vibration control with energy harvesting is a challenging topic due to conflicting goals: the first goal is to reduce the vibration of the host structure which vibrates in response to an external source and the second is to use the vibration to scavenge electric energy to supply sensors for condition monitoring. This paper proposes an analytical model to investigate the behavior of a rotational vibration absorber integrated with a piezoelectric energy harvesting device. Although that of a vibration absorber is a well-known problem, the introduction of piezoelectric transducers modifies its classical formulation. For this reason, new analytical results for optimal parameters are obtained and the differences with the rotational vibration absorber without energy harvesting are analyzed numerically. In addition, this work demonstrates that by an appropriate choice of electric parameters, it is possible to both scavenge electric energy and reduce the vibration of the host structure with a single device, obtaining a compromise between the two opposite goals.